507 results
Search Results
2. Recording and Analysis of Pole Figures by Computer
- Author
-
J. L. Alty
- Subjects
Physics ,Optics ,Computer program ,Hall effect ,business.industry ,Paper tape ,Goniometer ,General Physics and Astronomy ,Texture (crystalline) ,Tensor ,Pole figure ,business ,Sample (graphics) - Abstract
A computer program has been written to produce pole figures using the data from an x‐ray texture goniometer. The data are corrected for background and absorption. The pole figure is also stored on magnetic or paper tape in a form suitable for quantitative calculations. As an example, the Hall coefficient of a poly‐crystalline sample of a close‐packed hexagonal material is computed from the pole figure of the sample in terms of the single‐crystal components of the Hall tensor.
- Published
- 1968
3. Visualization of vibration and sound using scanning and holographic methods
- Author
-
E. Eugene Watson and Robert J. Hannon
- Subjects
Physics ,geography ,geography.geographical_feature_category ,business.industry ,Acoustics ,Holography ,General Physics and Astronomy ,Graph paper ,Vibrator (mechanical) ,Visualization ,law.invention ,Vibration ,Optics ,law ,Sound sources ,business ,Sound (geography) - Abstract
Two scanning techniques are now being used to determine the vibrational patterns and far‐field sound radiation of complex vibratory systems. One technique is a near‐field scanning apparatus which scans the vibrator and gives a three‐dimensional display on graph paper of the nodal patterns. The other scanning technique uses the principles of holography to locate far‐field sound sources on the vibrator. These two methods, coupled together, have demonstrated a unique capability to locate acoustic sources and hot spots on vibratory systems.
- Published
- 1974
4. Highly efficient meta-radiators with circular polarization
- Author
-
Ali Abdolali, Morteza Nadi, Hamid Rajabalipanah, and Ahmad Cheldavi
- Subjects
010302 applied physics ,Physics ,Coupling ,Floquet theory ,Axial ratio ,business.industry ,Aperture ,General Physics and Astronomy ,02 engineering and technology ,021001 nanoscience & nanotechnology ,01 natural sciences ,Directivity ,Optics ,0103 physical sciences ,Boundary value problem ,0210 nano-technology ,business ,Circular polarization ,Ground plane - Abstract
In this paper, circularly polarized metasurface radiators (meta-radiator) are elaborately designed with low-profile, small footprint, and highly efficient specifications. The proposed array consists of single-feed dense radiating meta-atoms that overall occupies a small area of 1.57 λ 0 × 1.57 λ 0 at f = 5.8 GHz. The inter-element coupling is involved by analyzing the contributing meta-atoms with Floquet boundary conditions. For demonstration purposes, an 8 × 8 sample of meta-radiators excited by an isolated network beneath the ground plane is fabricated. Both numerical and experimental results demonstrate that the meta-radiator exposes a pure left-hand circularly polarized radiation with a peak broadside directivity, a realized gain, and an axial ratio of 14.9 dBi, 14.2 dB, and 1.28 dB, respectively. Numerical simulations indicate that the aperture, radiation, and total efficiencies are as high as 99%, 97.5%, and 84.3%, respectively. In comparison with the conventional array antennas with similar performances, the proposed meta-radiator provides a higher aperture efficiency, in a simpler manner to achieve circular polarization, and more compact size as discussed throughout the paper. This new class of radiating architectures may find great potential applications in target detection systems and wireless communications.
- Published
- 2020
5. Optimized hybrid functionals for defect calculations in semiconductors
- Author
-
Bálint Aradi, Michael Lorke, Thomas Frauenheim, and Peter Deák
- Subjects
010302 applied physics ,Physics ,business.industry ,General Physics and Astronomy ,Diamond ,02 engineering and technology ,engineering.material ,021001 nanoscience & nanotechnology ,01 natural sciences ,Hybrid functional ,Computational physics ,Paramagnetism ,Semiconductor ,Atomic electron transition ,Photovoltaics ,0103 physical sciences ,engineering ,Density functional theory ,0210 nano-technology ,business ,Mixing (physics) - Abstract
Defects influence the electronic and optical properties of crystals, so their identification is crucial to develop device technology for materials of micro-/optoelectronics and photovoltaics. The identification requires the accurate calculation of the electronic transitions and the paramagnetic properties of defects. The achievable accuracy is strongly limited in the case of the (semi)local approximations to density functional theory, because of the underestimation of the gap and of the degree of localization. In the past two decades, hybrid functionals, mixing semilocal and nonlocal exchange semiempirically, have emerged as an alternative. Very often, however, the parameters of such hybrids have to be tuned from material to material. In this paper, we describe the theoretical foundations for the proper tuning and show that if the relative positions of the band edge states are well reproduced, and the generalized Koopmans's theorem is fulfilled by the given parameterization, the calculated defect levels and localizations can be very accurate. As demonstrated here, this can be achieved with the two-parameter Heydt-Scuseria-Ernzerhof hybrid, HSE(α,μ) for diamond, Si, Ge, TiO2, GaAs, CuGaS(Se)2, GaSe, GaN, and Ga2O3. The paper describes details of the parameterization process and discusses the limitations of optimizing HSE functionals. Based on the gained experience, future directions for improving exchange functionals are also provided.
- Published
- 2019
6. Design of broadband impedance-matching Bessel lens with acoustic metamaterials
- Author
-
Yue Zhao, Hui Yuan Dong, Suwei Min, Fengfeng Chi, Bin Li, S. L. Liu, Songwei Zhao, and Jie Cheng
- Subjects
010302 applied physics ,Physics ,business.industry ,Impedance matching ,Physics::Optics ,General Physics and Astronomy ,02 engineering and technology ,021001 nanoscience & nanotechnology ,01 natural sciences ,Signal ,law.invention ,Lens (optics) ,symbols.namesake ,Optics ,law ,0103 physical sciences ,symbols ,Reflection (physics) ,Bessel beam ,Physics::Accelerator Physics ,0210 nano-technology ,business ,Refractive index ,Bessel function ,Energy (signal processing) - Abstract
In this paper, a gradient-index lens is designed to implement an acoustic Bessel beam. Here, the wave from the point source is reshaped to the Bessel beam with the energy concentrated near the axial direction and almost no divergence. The two-dimensional distribution of the gradient refractive index is obtained based on the analysis of the impedance matching theory. The interface reflection is reduced significantly due to the impedance matching with air. The effect of the acoustic Bessel lens is found to work in a broadband with the use of the subwavelength unit cell and the finite-element simulations. Our results may provide the potential applications for medical ultrasound imaging and signal detection.In this paper, a gradient-index lens is designed to implement an acoustic Bessel beam. Here, the wave from the point source is reshaped to the Bessel beam with the energy concentrated near the axial direction and almost no divergence. The two-dimensional distribution of the gradient refractive index is obtained based on the analysis of the impedance matching theory. The interface reflection is reduced significantly due to the impedance matching with air. The effect of the acoustic Bessel lens is found to work in a broadband with the use of the subwavelength unit cell and the finite-element simulations. Our results may provide the potential applications for medical ultrasound imaging and signal detection.
- Published
- 2019
7. Manipulating photonic spin accumulation with a magnetic field
- Author
-
Lan Luo, Zhiyou Zhang, Jinglei Du, Jiangdong Qiu, Xiong Liu, Linguo Xie, Zhaoxue Li, and Yu He
- Subjects
010302 applied physics ,Physics ,Brewster's angle ,Spintronics ,business.industry ,Linear polarization ,Physics::Optics ,General Physics and Astronomy ,02 engineering and technology ,021001 nanoscience & nanotechnology ,01 natural sciences ,Magnetic field ,symbols.namesake ,0103 physical sciences ,symbols ,Light beam ,Optoelectronics ,Weak measurement ,Photonics ,0210 nano-technology ,Spin (physics) ,business - Abstract
In this paper, we propose a simple and effective method to manipulate photonic spin accumulation with an applied magnetic field. When a linearly polarized Gaussian light beam is reflected from the prism-air interface at the Brewster angle, the magnitude and direction of the photonic spin accumulation can be flexibly modulated by adjusting the applied magnetic field. Importantly, the maximum displacement of photonic spin accumulation can reach about 39.14 μ m, which provides the opportunity to directly observe photonic spin accumulation without weak measurements. These findings may hold potential applications for manipulating and detecting the electron spin current, leading to the development of a new spintronic device.In this paper, we propose a simple and effective method to manipulate photonic spin accumulation with an applied magnetic field. When a linearly polarized Gaussian light beam is reflected from the prism-air interface at the Brewster angle, the magnitude and direction of the photonic spin accumulation can be flexibly modulated by adjusting the applied magnetic field. Importantly, the maximum displacement of photonic spin accumulation can reach about 39.14 μ m, which provides the opportunity to directly observe photonic spin accumulation without weak measurements. These findings may hold potential applications for manipulating and detecting the electron spin current, leading to the development of a new spintronic device.
- Published
- 2019
8. Twisted beam shaping by plasma photonic crystal
- Author
-
Hassan Mehdian, Davod Nobahar, and K. Hajisharifi
- Subjects
Physics ,Birefringence ,Number density ,business.industry ,Physics::Optics ,General Physics and Astronomy ,Plasma ,01 natural sciences ,010305 fluids & plasmas ,Magnetic field ,010309 optics ,Angular spectrum method ,Optics ,0103 physical sciences ,business ,Beam (structure) ,Photonic crystal ,Matrix method - Abstract
In this paper, we investigate the strong modification and reshaping of the Laguerre-Gaussian (LG) beam using a tailored magnetized plasma photonic crystal (PPC), based on the angular spectrum expansion and 4 × 4 matrix method. It is numerically shown that by manipulating both external magnetic field and plasma number density, the reflected and transmitted beam shape is perfectly controlled. In addition, to show the domain role of magnetized PPC birefringence in the shaping of the twisted beam (TB), vertical incidence and oblique incidence of the LG beam are analyzed. We believe that these results open the door to use PPC structures in modulating the shape of a reference TB for new optical traps. Meanwhile, this study gives a new insight into the diagnostic of plasma systems using analyses of TB shapes.In this paper, we investigate the strong modification and reshaping of the Laguerre-Gaussian (LG) beam using a tailored magnetized plasma photonic crystal (PPC), based on the angular spectrum expansion and 4 × 4 matrix method. It is numerically shown that by manipulating both external magnetic field and plasma number density, the reflected and transmitted beam shape is perfectly controlled. In addition, to show the domain role of magnetized PPC birefringence in the shaping of the twisted beam (TB), vertical incidence and oblique incidence of the LG beam are analyzed. We believe that these results open the door to use PPC structures in modulating the shape of a reference TB for new optical traps. Meanwhile, this study gives a new insight into the diagnostic of plasma systems using analyses of TB shapes.
- Published
- 2018
9. Calculation of a capacitively-coupled floating gate array toward quantum annealing machine
- Author
-
Yusuke Higashi, Tetsufumi Tanamoto, and Jun Deguchi
- Subjects
Physics ,business.industry ,Capacitive sensing ,Quantum annealing ,General Physics and Astronomy ,NAND gate ,02 engineering and technology ,021001 nanoscience & nanotechnology ,Topology ,01 natural sciences ,Semiconductor ,Gate array ,Qubit ,0103 physical sciences ,Miniaturization ,010306 general physics ,0210 nano-technology ,business ,Quantum - Abstract
Quantum annealing machines based on superconducting qubits, which have the potential to solve optimization problems faster than digital computers, are of great interest not only to researchers but also to the general public. In this paper, we propose a quantum annealing machine based on a semiconductor floating gate (FG) array. The purpose of using the architecture of nand flash memories is to reuse a mature technology to create large arrays of silicon qubits. Current high-density nand flash memories use sufficiently small FG cells to make the number of electrons stored in each cell small and countable. The high packing density of these cells creates mutual capacitive couplings that can be used to generate cell-to-cell interactions. We explore these characteristics to derive an Ising Hamiltonian for the FG system in the single-electron regime. Considering the size of a cell (10 nm), the ideal operation temperature of a quantum annealer based on FG cells is estimated to be approximately that of liquid nitrogen. Assuming the parameters of a commercial 64 Gbit nand, we estimate that it is possible to create 2-megabyte (MB) qubit systems solely using conventional fabrication processes. Our proposal demonstrates that a large qubit system can be obtained as a natural extension of the miniaturization of commercial-grade electronics, although more effort will likely be required to achieve high-quality qubits.Quantum annealing machines based on superconducting qubits, which have the potential to solve optimization problems faster than digital computers, are of great interest not only to researchers but also to the general public. In this paper, we propose a quantum annealing machine based on a semiconductor floating gate (FG) array. The purpose of using the architecture of nand flash memories is to reuse a mature technology to create large arrays of silicon qubits. Current high-density nand flash memories use sufficiently small FG cells to make the number of electrons stored in each cell small and countable. The high packing density of these cells creates mutual capacitive couplings that can be used to generate cell-to-cell interactions. We explore these characteristics to derive an Ising Hamiltonian for the FG system in the single-electron regime. Considering the size of a cell (10 nm), the ideal operation temperature of a quantum annealer based on FG cells is estimated to be approximately that of liquid nitr...
- Published
- 2018
10. Energy filtering in silicon nanowires and nanosheets using a geometric superlattice and its use for steep-slope transistors
- Author
-
Arnout Beckers, Maarten Thewissen, and Bart Sorée
- Subjects
Materials science ,Silicon ,Superlattice ,Nanowire ,General Physics and Astronomy ,chemistry.chemical_element ,02 engineering and technology ,01 natural sciences ,law.invention ,quantum ,Effective mass (solid-state physics) ,law ,0103 physical sciences ,Quantum tunnelling ,010302 applied physics ,business.industry ,Subthreshold conduction ,Physics ,field-effect transistors ,Transistor ,Condensed Matter::Mesoscopic Systems and Quantum Hall Effect ,021001 nanoscience & nanotechnology ,chemistry ,transport ,Optoelectronics ,Field-effect transistor ,0210 nano-technology ,business ,devices - Abstract
This paper investigates energy filtering in silicon nanowires and nanosheets by resonant electron tunneling through a geometric superlattice. A geometric superlattice is any kind of periodic geometric feature along the transport direction of the nanowire or nanosheet. Multivalley quantum-transport simulations are used to demonstrate the manifestation of minibands and minibandgaps in the transmission spectra of such a superlattice. We find that the presence of different valleys in the conduction band of silicon favors a nanowire with a rectangular cross section for effective energy filtering. The obtained energy filter can consequently be used in the source extension of a field-effect transistor to prevent high-energy electrons from contributing to the leakage current. Self-consistent Schrodinger-Poisson simulations in the ballistic limit show minimum subthreshold swings of 6 mV/decade for geometric superlattices with indentations. The obtained theoretical performance metrics for the simulated devices are compared with conventional III-V superlatticeFETs and TunnelFETs. The adaptation of the quantum transmitting boundary method to the finite-element simulation of 3-D structures with anisotropic effective mass is presented in Appendixes A and B. Our results bare relevance in the search for steep-slope transistor alternatives which are compatible with the silicon industry and can overcome the power-consumption bottleneck inherent to standard CMOS technologies.This paper investigates energy filtering in silicon nanowires and nanosheets by resonant electron tunneling through a geometric superlattice. A geometric superlattice is any kind of periodic geometric feature along the transport direction of the nanowire or nanosheet. Multivalley quantum-transport simulations are used to demonstrate the manifestation of minibands and minibandgaps in the transmission spectra of such a superlattice. We find that the presence of different valleys in the conduction band of silicon favors a nanowire with a rectangular cross section for effective energy filtering. The obtained energy filter can consequently be used in the source extension of a field-effect transistor to prevent high-energy electrons from contributing to the leakage current. Self-consistent Schrodinger-Poisson simulations in the ballistic limit show minimum subthreshold swings of 6 mV/decade for geometric superlattices with indentations. The obtained theoretical performance metrics for the simulated devices are ...
- Published
- 2018
11. Photonic Hall effect
- Author
-
L. Abaspour, D. Jahani, A. Alidoust Ghatar, and Tayebeh Jahani
- Subjects
Physics ,Quantum optics ,Condensed Matter - Mesoscale and Nanoscale Physics ,Condensed matter physics ,business.industry ,Graphene ,FOS: Physical sciences ,General Physics and Astronomy ,02 engineering and technology ,Quantum Hall effect ,021001 nanoscience & nanotechnology ,01 natural sciences ,Transfer matrix ,law.invention ,Magnetic field ,law ,Hall effect ,Mesoscale and Nanoscale Physics (cond-mat.mes-hall) ,0103 physical sciences ,Photonics ,010306 general physics ,0210 nano-technology ,business ,Photonic crystal - Abstract
In this work, we report on the emergence of a photonic Hall effect (PHE) system within a narrow filtered background of a one-dimensional defective optical dielectric structure with graphene under the influence of a constant magnetic field regime. It is observed that at low temperature and relatively strong applied magnetic fields, electromagnetic defective transmission spectra corresponding to the two decoupled right- and left-handed polarized modes possess a step-like transmission feature which is referred to as “quantum Hall defect modes” (QHD modes or QHDs) in this paper. Tunable growing transitional transmission steps for QHDs with increasing magnetic field intensity were shown to be possible. Observation of sensitive magneto-transmission oscillations to the thermal excitations in the last plateaus slowly ascending toward unity is another special feature noted in this work. The results of this study, which is carried out based on rapid standard calculations for the transfer matrix approach is supplied with commercial simulations marking the first PHE system, promise an proper candidate for new photonic applications, especially new tunable magneto-based lenses and photonic magneto-thermal sensors.In this work, we report on the emergence of a photonic Hall effect (PHE) system within a narrow filtered background of a one-dimensional defective optical dielectric structure with graphene under the influence of a constant magnetic field regime. It is observed that at low temperature and relatively strong applied magnetic fields, electromagnetic defective transmission spectra corresponding to the two decoupled right- and left-handed polarized modes possess a step-like transmission feature which is referred to as “quantum Hall defect modes” (QHD modes or QHDs) in this paper. Tunable growing transitional transmission steps for QHDs with increasing magnetic field intensity were shown to be possible. Observation of sensitive magneto-transmission oscillations to the thermal excitations in the last plateaus slowly ascending toward unity is another special feature noted in this work. The results of this study, which is carried out based on rapid standard calculations for the transfer matrix approach is supplied...
- Published
- 2018
12. Frequency graded 1D metamaterials: A study on the attenuation bands
- Author
-
Raj Das, Emilio P. Calius, and Arnab Banerjee
- Subjects
010302 applied physics ,Physics ,business.industry ,Wave propagation ,Acoustics ,Attenuation ,General Physics and Astronomy ,Metamaterial ,02 engineering and technology ,Low frequency ,021001 nanoscience & nanotechnology ,01 natural sciences ,Vibration ,Resonator ,Optics ,Effective mass (solid-state physics) ,0103 physical sciences ,Wideband ,0210 nano-technology ,business - Abstract
Depending on the frequency, waves can either propagate (transmission band) or be attenuated (attenuation band) while travelling through a one-dimensional spring-mass chain with internal resonators. The literature on wave propagation through a 1D mass-in-mass chain is vast and continues to proliferate because of its versatile applicability in condensed matter physics, optics, chemistry, acoustics, and mechanics. However, in all these areas, a uniformly periodic arrangement of identical linear resonating units is normally used which limits the attenuation band to a narrow frequency range. To counter this limitation of linear uniformly periodic metamaterials, the attenuation bandwidth in a one-dimensional finite chain with frequency graded linear internal resonators are investigated in this paper. The result shows that a properly tuned frequency graded arrangement of resonating units can extend the upper part of the attenuation band of 1D metamaterial theoretically up to infinity and also increases the lower part of the attenuation bandwidth by around 40% of an equivalent uniformly periodic metamaterial without increasing the mass. Therefore, the frequency graded metamaterials can be a potential solution towards low frequency and wideband acoustic or vibration insulation. In addition, this paper provides analytical expressions for the attenuation and transmission frequency limits for a periodic mass-in-mass metamaterial and demonstrates the attenuation band is generated by the high absolute value of the effective mass not only due to the negative effective mass.
- Published
- 2017
13. Fano resonances in photonic crystal nanobeams side-coupled with nanobeam cavities
- Author
-
Anhui Liang, Zi-Ming Meng, and Zhi-Yuan Li
- Subjects
Physics ,Waveguide (electromagnetism) ,business.industry ,Physics::Optics ,General Physics and Astronomy ,Fano resonance ,Resonance ,02 engineering and technology ,021001 nanoscience & nanotechnology ,Coupled mode theory ,01 natural sciences ,010309 optics ,Resonator ,Optical modulator ,0103 physical sciences ,Optoelectronics ,Photonics ,0210 nano-technology ,business ,Photonic crystal - Abstract
Fano resonances usually arise when a narrow resonance or discrete state and a broad resonance or continuum state are coupled. In this paper, we theoretically and numerically study asymmetric Fano line shape realized in a photonic crystal nanobeam (PCN) side-coupled with a photonic crystal nanobeam cavity (PCNC). Asymmetric transmission profiles with a transmission peak and a transmission valley are obtained for a low index concentrated cavity mode. The transmission valley, associated with the destructive interference, of our PCN-PCNC structures is deeper than that of a waveguide or Fabry-Perot resonator side-coupled with a PCNC structure. Through changing the position of the photonic band gap (PBG) of the PCN, we can utilize the high or low frequency band edge modes and the Fano transmission profiles can be further controlled. The transmission spectra of our PCN-PCNC structures can be well fitted by the Fano resonance formula and agree qualitatively with the prediction made by the temporal coupled mode theory. By using the band edge modes of the PCN as the continuum state instead of a usual broad resonance, we have demonstrated a new way to generate a prominent Fano resonance. Our PCN-PCNC structures are compact and feasible to achieve large-scale high-performance integrated photonic devices, such as optical modulators or switches.Fano resonances usually arise when a narrow resonance or discrete state and a broad resonance or continuum state are coupled. In this paper, we theoretically and numerically study asymmetric Fano line shape realized in a photonic crystal nanobeam (PCN) side-coupled with a photonic crystal nanobeam cavity (PCNC). Asymmetric transmission profiles with a transmission peak and a transmission valley are obtained for a low index concentrated cavity mode. The transmission valley, associated with the destructive interference, of our PCN-PCNC structures is deeper than that of a waveguide or Fabry-Perot resonator side-coupled with a PCNC structure. Through changing the position of the photonic band gap (PBG) of the PCN, we can utilize the high or low frequency band edge modes and the Fano transmission profiles can be further controlled. The transmission spectra of our PCN-PCNC structures can be well fitted by the Fano resonance formula and agree qualitatively with the prediction made by the temporal coupled mode th...
- Published
- 2017
14. Quantum well photoconductors in infrared detector technology
- Author
-
Antoni Rogalski
- Subjects
Physics ,business.industry ,Photoresistor ,Bolometer ,General Physics and Astronomy ,Photodetector ,law.invention ,Photodiode ,law ,Figure of merit ,Optoelectronics ,Infrared detector ,Quantum well infrared photodetector ,business ,Quantum well - Abstract
The paper compares the achievements of quantum well infrared photodetector (QWIP) technology with those of competitive technologies, with the emphasis on the material properties, device structure, and their impact on focal plane array (FPA) performance. Special attention is paid to two competitive technologies, QWIP and HgCdTe, in the long-wavelength IR (LWIR) and very-long-wavelength IR (VLWIR) spectral ranges. Because so far, the dialogue between the QWIP and HgCdTe communities is limited, the paper attempts to settle the main issues of both technologies. Such an approach, however, requires the presentation of fundamental limits to the different types of detectors, which is made at the beginning. To write the paper more clearly for readers, many details are included in the Appendix. In comparative studies both photon and thermal detectors are considered. Emphasis is placed on photon detectors. In this group one may distinguish HgCdTe photodiodes, InSb photodiodes, and doped silicon detectors. The potential performance of different materials as infrared detectors is examined utilizing the α/G ratio, where α is the absorption coefficient and G is the thermal generation rate. It is demonstrated that LWIR QWIP’s cannot compete with HgCdTe photodiodes as single devices, especially at higher operating temperatures (>70 K). This is due to the fundamental limitations associated with intersubband transitions. The advantage of HgCdTe is, however, less distinct at temperatures lower than 50 K due to problems inherent in the HgCdTe material (p-type doping, Shockley–Read recombination, trap-assisted tunneling, surface and interface instabilities). Even though QWIP is a photoconductor, several of its properties, such as high impedance, fast response time, long integration time, and low power consumption, comply well with the requirements imposed on the fabrication of large FPA’s. Due to a high material quality at low temperatures, QWIP has potential advantages over HgCdTe in the area of VLWIR FPA applications in terms of array size, uniformity, yield, and cost of the systems. The performance figures of merit of state-of-the-art QWIP and HgCdTe FPA’s are similar because the main limitations come from the readout circuits. Performance is, however, achieved with very different integration times. The choice of the best technology is therefore driven by the specific needs of a system. In the case of readout-limited detectors a low photoconductive gain increases the signal-to-noise ratio and a QWIP FPA can have a better noise equivalent difference temperature than an HgCdTe FPA with a charge well of similar size. Both HgCdTe photodiodes and QWIP’s offer multicolor capability in the MWIR and LWIR range. Powerful possibilities offered by QWIP technology are associated with VLWIR FPA applications and with multicolor detection. The intrinsic advantage of QWIP’s in this niche is due to the relative ease of growing multicolor structures with a very low defect density.
- Published
- 2003
15. Pull-in analysis of non-uniform microcantilever beams under large deflection
- Author
-
Sajal Singh, Ashok Kumar Pandey, and Prem Pal
- Subjects
Physics ,Cantilever ,business.industry ,Mathematical analysis ,Single-mode optical fiber ,General Physics and Astronomy ,Resonator ,Optics ,Normal mode ,Physics::Accelerator Physics ,Galerkin method ,business ,Linear equation ,Beam (structure) ,Voltage - Abstract
Cantilever beams under the influence of electrostatic force form an important subclass of microelectromechanical system(MEMS) and nanoelectromechanical system. Most of the studies concerning these micro-nano resonators are centered around uniform cantilever beams. In this paper, we have investigated another class of micro-resonators consisting of non-uniform cantilever beams. The study is focused around investigating pull-in voltage and resonance frequency of non-uniform cantilever beams when they operate in the linear regime about different static equilibriums. In this paper, we term this frequency as “linear frequency.” Calculation of the linear frequency is done at different static equilibriums corresponding to different DC voltages. We have studied two classes of beams, one with increasing cross sectional area from the clamped edge (diverging beam) and other with decreasing cross sectional area from the clamped edge (converging beam). Within each class, we have investigated beams with linear as well as quartic variation in width. We start by obtaining Euler beam equation for non-uniform cantilever beams considering large deflection and their corresponding exact mode shapes from the linear equation. Subsequently, using the Galerkin method based on single mode approximation, we obtain static and dynamic modal equations for finding pull-in voltage and resonance frequency as a function of DC voltage, respectively. We found that the linear frequency of converging beams increases with increase in non-uniform parameter (α) while those of diverging beams decreases with α. A similar trend is observed for pull-in voltage. Within the converging class, beams with quartic variation in width show significant increase in both frequency and pull-in voltage as compared to corresponding linearly tapered beams. In quantitative terms, converging beams with quartic variation in width and α=−0.6 showed an increase in linear frequency by a factor of 2.5 times and pull-in voltage by 2 times as compared to commonly used uniform beams. Our investigation can prove to be a step forward in designing highly sensitive MEMS sensors and actuators.
- Published
- 2015
16. Hybrid dispersive media with controllable wave propagation: A new take on smart materials
- Author
-
Edgar A. Flores Parra, Andrea Bergamini, Manuel Zündel, Massimo Ruzzene, Tommaso Delpero, and Paolo Ermanni
- Subjects
Physics ,Wave propagation ,business.industry ,Attenuation ,General Physics and Astronomy ,Metamaterial ,Transverse wave ,law.invention ,Optics ,Surface wave ,law ,Dispersion relation ,Wavenumber ,business ,Waveguide - Abstract
In this paper, we report on the wave transmission characteristics of a hybrid one dimensional (1D) medium. The hybrid characteristic is the result of the coupling between a 1D mechanical waveguide in the form of an elastic beam, supporting the propagation of transverse waves and a discrete electrical transmission line, consisting of a series of inductors connected to ground through capacitors. The capacitors correspond to a periodic array of piezoelectric patches that are bonded to the beam and that couple the two waveguides. The coupling leads to a hybrid medium that is characterized by a coincidence condition for the frequency/wavenumber value corresponding to the intersection of the branches of the two waveguides. In the frequency range centered at coincidence, the hybrid medium features strong attenuation of wave motion as a result of the energy transfer towards the electrical transmission line. This energy transfer, and the ensuing attenuation of wave motion, is alike the one obtained through internal resonating units of the kind commonly used in metamaterials. However, the distinct shape of the dispersion curves suggests how this energy transfer is not the result of a resonance and is therefore fundamentally different. This paper presents the numerical investigation of the wave propagation in the considered media, it illustrates experimental evidence of wave transmission characteristics and compares the performance of the considered configuration with that of internal resonating metamaterials. In addition, the ability to conveniently tune the dispersion properties of the electrical transmission line is exploited to adapt the periodicity of the domain and to investigate diatomic periodic configurations that are characterized by a richer dispersion spectrum and broader bandwidth of wave attenuation at coincidence. The medium consisting of mechanical, piezoelectric, and analog electronic elements can be easily interfaced to digital devices to offer a novel approach to smart materials.
- Published
- 2015
17. Effective field enhancement factor and the influence of emitted space charge
- Author
-
John R. Harris, Matthew LaCour, Ken Golby, John J. Petillo, Don Shiffler, Wilkin Tang, and Kevin L. Jensen
- Subjects
Physics ,Surface (mathematics) ,Field (physics) ,business.industry ,General Physics and Astronomy ,Space charge ,Cathode ,Computational physics ,law.invention ,Field electron emission ,Optics ,law ,Surface roughness ,Work function ,business ,Common emitter - Abstract
Although Fowler and Nordheim developed the basics of field emission nearly one century ago with their introduction of the Fowler-Nordheim equation (FNE), the topic continues to attract research interest particularly with the development of new materials that have been proposed as field emitters. The first order analysis of experiments typically relies upon the FNE for at minimum a basic understand of the physical emission process and its parameters of emission. The three key parameters in the FNE are the work function, emission area, and field enhancement factor, all of which can be difficult to determine under experimental conditions. This paper focuses in particular, on the field enhancement factor β. It is generally understood that β provides an indication of the surface roughness or sharpness of a field emitter cathode. However, in this paper, we experimentally and computationally demonstrate that cathodes with highly similar surface morphologies can manifest quite different field enhancements solely through having different emission regions. This fact can cause one to re-interpret results in which a single sharp emitter is proposed to dominate the emission from a field emitting cathode.
- Published
- 2015
18. Disorder persistent transparency within the bandgap of a periodic array of acoustic Helmholtz resonators
- Author
-
Vincent Pagneux, Agnès Maurel, Olivier Richoux, Laboratoire d'Acoustique de l'Université du Mans (LAUM), Le Mans Université (UM)-Centre National de la Recherche Scientifique (CNRS), Soprano, Centre National de la Recherche Scientifique (CNRS)-Le Mans Université (UM), Institut Langevin - Ondes et Images (UMR7587) (IL), Sorbonne Université (SU)-Ecole Superieure de Physique et de Chimie Industrielles de la Ville de Paris (ESPCI Paris), and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Paris (UP)-Centre National de la Recherche Scientifique (CNRS)
- Subjects
[PHYS.PHYS.PHYS-CLASS-PH]Physics [physics]/Physics [physics]/Classical Physics [physics.class-ph] ,Optical resonators ,Band gap ,Helmholtz resonator ,WAVES ,Gaussian processes ,General Physics and Astronomy ,PROPAGATION ,Multiple resonance ,01 natural sciences ,Electronic band structure ,010305 fluids & plasmas ,[SPI]Engineering Sciences [physics] ,symbols.namesake ,Resonator ,Optics ,Lattice (order) ,0103 physical sciences ,SCATTERING ,010306 general physics ,Bloch wave ,[PHYS]Physics [physics] ,[PHYS.MECA.VIBR]Physics [physics]/Mechanics [physics]/Vibrations [physics.class-ph] ,Physics ,Wave propagation ,Periodic lattice ,business.industry ,Crystal optics ,Acoustics ,[PHYS.MECA.ACOU]Physics [physics]/Mechanics [physics]/Acoustics [physics.class-ph] ,Acoustic wave propagation ,Helmholtz free energy ,symbols ,Microphones ,business - Abstract
International audience; In this paper, the influence of disorder on 1D periodic lattice of resonant scatterers is inspected. These latter have multiple resonance frequencies which produce band gaps in the transmission spectrum. One peculiarity of the presented system is that it is chosen with a nearly perfect overlap between the Bragg and the second hybridization band gaps. In the case of a perfectly ordered lattice, and around this overlap, this produces a narrow transparency band within a large second bandgap. As expected, the effect of the disorder is generally to increase the width of the band gaps. Nevertheless, the transparency band appears to be robust with respect to an increase in the disorder. In this paper, we study this effect by means of experimental investigations and numerical simulations.
- Published
- 2015
19. Influence of curvature on the device physics of thin film transistors on flexible substrates
- Author
-
Sanjiv Sambandan and Rex Amalraj
- Subjects
Physics ,business.industry ,General Physics and Astronomy ,Insulator (electricity) ,Curvature ,Capacitance ,Flexible electronics ,Poisson's ratio ,symbols.namesake ,Buckling ,Thin-film transistor ,symbols ,Optoelectronics ,Instrumentation Appiled Physics ,Thin film ,business - Abstract
Thin film transistors (TFTs) on elastomers promise flexible electronics with stretching and bending. Recently, there have been several experimental studies reporting the behavior of TFTs under bending and buckling. In the presence of stress, the insulator capacitance is influenced due to two reasons. The first is the variation in insulator thickness depending on the Poisson ratio and strain. The second is the geometric influence of the curvature of the insulator-semiconductor interface during bending or buckling. This paper models the role of curvature on TFT performance and brings to light an elegant result wherein the TFT characteristics is dependent on the area under the capacitance-distance curve. The paper compares models with simulations and explains several experimental findings reported in literature. (C) 2014 AIP Publishing LLC.
- Published
- 2014
20. Response of interferometer based probe systems to photodisplacement in layered media
- Author
-
M. Liu, M. B. Suddendorf, and Michael Geoffrey Somekh
- Subjects
Physics ,Interferometry ,Thermoelastic damping ,Optics ,business.industry ,Optical transfer function ,Astronomical interferometer ,General Physics and Astronomy ,business ,Sample (graphics) ,Refractive index ,Transfer function ,Displacement (vector) - Abstract
This paper presents a detailed theory which describes the response of a focused interferometer when a modulated laser source is incident upon a layered sample. In order to solve this problem it is necessary to solve the thermoelastic equations for a layered sample. The paper presents an analytical solution obtained using a symbolic manipulation program (reduce). In particular, we point out that the analytical form of the solution is necessary to achieve numerically stable results. In addition to calculating the actual displacement of the sample surface, the response of the instrument is considered in detail, in terms of the refractive index changes of the air above the sample and the optical transfer function of the probe optics.
- Published
- 1994
21. Determination of the interaction coordinate in drift detectors through the timing of induced signals
- Author
-
F. E. Zocchi, E. Gatti, and Marco Sampietro
- Subjects
Physics ,Interaction point ,Physics::Instrumentation and Detectors ,business.industry ,Detector ,General Physics and Astronomy ,Centroid ,Semiconductor device ,Particle detector ,Semiconductor detector ,Anode ,Optics ,Electric field ,business - Abstract
The time centroid of the current pulse induced at the anode of a semiconductor drift detector is calculated as a function of the interaction coordinate for arbitrary drifting fields. The effects of its behavior on the determination of the absolute position of the interaction point are studied. For a typical bias condition of the detector, the paper shows that an error up to few hundred micrometers is made in the position reconstruction of the event if the described effects of the induction are not taken into account. The paper also shows that the time shift due to the perturbation of the drifting field caused by the discreteness of the field electrodes, is only of less than 1 ns, and therefore negligible in most applications.
- Published
- 1993
22. Application of the transfer function method in calculations of the directivity pattern of ultrasonic transducer
- Author
-
W. Pajewski and Piotr Kielczynski
- Subjects
Physics ,business.industry ,Main lobe ,Acoustics ,General Physics and Astronomy ,Directivity ,Transfer function ,Radiation pattern ,symbols.namesake ,Optics ,Transducer ,Normal mode ,symbols ,Ultrasonic sensor ,business ,Bessel function - Abstract
In this paper the authors applied an original transfer function method for calculations of radiation patterns in the case of Bessel circular transducers. It is known that the amplitudes of some natural vibration modes of circular plates are Bessel functions of zero order [R. R. Aggarval, JASA 24, 463 (1952)]. In the paper the natural vibrational modes of a circular disk‐shaped ultrasonic transducer were employed. As it follows from the numerical calculations, it is possible to obtain for Bessel‐like transducers the nondiffracting main lobe. The latter is in accordance with the suggestions of the paper [J. Durnin, J. Opt. Soc. Am. 4, 651 (1987)].
- Published
- 1991
23. Numerical study of the influence of applied voltage on the current balance factor of single layer organic light-emitting diodes
- Author
-
Fei-Ping Lu, Yong-Zhong Xing, and Xiao-Bin Liu
- Subjects
Physics ,Electron mobility ,business.industry ,General Physics and Astronomy ,law.invention ,law ,OLED ,Optoelectronics ,Electric potential ,Electric current ,business ,Current density ,Voltage ,Light-emitting diode ,Diode - Abstract
Current balance factor (CBF) value, the ratio of the recombination current density and the total current density of a device, has an important function in fluorescence-based organic light-emitting diodes (OLEDs), as well as in the performance of the organic electrophosphorescent devices. This paper investigates the influence of the applied voltage of a device on the CBF value of single layer OLED based on the numerical model of a bipolar single layer OLED with organic layer trap free and without doping. Results show that the largest CBF value can be achieved when the electron injection barrier ( ϕ n ) is equal to the hole injection barrier ( ϕ p ) in the lower voltage region at any instance. The largest CBF in the higher voltage region can be achieved in the case of ϕ n > ϕ p under the condition of electron mobility ( μ 0 n ) > hole mobility ( μ 0 p ), whereas the result for the case of μ 0 n μ 0 p , is opposite. The largest CBF when μ 0 n = μ 0 p can be achieved in the case of ϕ n = ϕ p in the entire region of the applied voltage. In addition, the CBF value of the device increases with increasing applied voltage. The results obtained in this paper can present an in-depth understanding of the OLED working mechanism and help in the future fabrication of high efficiency OLEDs.
- Published
- 2014
24. Numerical study of Lamb waves band structure in one-dimensional phononic crystal slabs with the anti-symmetric boundary structure
- Author
-
Yuanwei Yao, Pingping Huang, Xin Zhang, and Fugen Wu
- Subjects
Physics ,Condensed matter physics ,Band gap ,business.industry ,General Physics and Astronomy ,Boundary (topology) ,Displacement (vector) ,Crystal ,Boundary layer ,Lamb waves ,Optics ,Slab ,business ,Electronic band structure - Abstract
This paper theoretically and numerically investigates the propagation of Lamb waves in a one-dimensional phononic crystal slab bordered with anti-symmetric boundary layers. The results show that the band structure of the anti-symmetric boundary phononic crystal is significantly different from those presented in the papers available. The eigenmodes displacement fields reveal that there is an essential distinction in the formation of the band gap between the anti-symmetric and the symmetric boundary model. On the other hand, the thickness of the boundary layers can remarkably change the width and the location of the band gaps. Furthermore, the variation of the phononic crystal band gaps and the band pinning elimination show the band gaps are sensitive to the degree of stagger of the boundary layers, and different band gap has a different response to the profile of the boundary. In other words, the topological distribution of the boundary layer has an influence on the band structures.
- Published
- 2014
25. Interactions of collinear acoustic waves propagating along pure mode directions of crystals
- Author
-
Wenhua Jiang, Xiaozhou Liu, Wenwu Cao, and Zheng Jiang
- Subjects
Physics ,Imagination ,business.industry ,media_common.quotation_subject ,General Physics and Astronomy ,Crystal structure ,Acoustic wave ,Point group ,Computational physics ,Crystal ,Nonlinear system ,Third order ,Optics ,Elasticity (economics) ,business ,media_common - Abstract
Previous studies on the interaction of collinear acoustic waves have been devoted to waves propagating along pure modes directions of cubic crystals. In this paper, we show that the calculations can be readily extended to all crystal point groups. Nonlinearity parameters characterizing the nonlinear interactions are defined here. The effective third order elastic constants involved in the parameters can be calculated by using the method presented in this paper. Our results are very useful for the study of elastic nonlinearity of crystals with any given symmetry.
- Published
- 2014
26. Simulations of the spontaneous emission of a quantum dot near a gap plasmon waveguide
- Author
-
Angus Mcleod, Kristy C. Vernon, and Chamanei S. Perera
- Subjects
Physics ,business.industry ,Surface plasmon ,Single-mode optical fiber ,Physics::Optics ,General Physics and Astronomy ,Condensed Matter::Mesoscopic Systems and Quantum Hall Effect ,Molecular physics ,law.invention ,law ,Quantum dot ,Quantum dot laser ,Optoelectronics ,Spontaneous emission ,business ,Nonlinear Sciences::Pattern Formation and Solitons ,Quantum ,Waveguide ,Plasmon - Abstract
In this paper, we modeled a quantum dot at near proximity to a gap plasmon waveguide to study the quantum dot-plasmon interactions. Assuming that the waveguide is single mode, this paper is concerned about the dependence of spontaneous emission rate of the quantum dot on waveguide dimensions such as width and height. We compare coupling efficiency of a gap waveguide with symmetric configuration and asymmetric configuration illustrating that symmetric waveguide has a better coupling efficiency to the quantum dot. We also demonstrate that optimally placed quantum dot near a symmetric waveguide with 50 nm × 50 nm cross section can capture 80% of the spontaneous emission into a guided plasmon mode.
- Published
- 2014
27. Terahertz quantum-well photodetectors: Design, performance, and improvements
- Author
-
Youyi Zhang, Shan-Tao Zhang, Yintang Yang, Wenzhong Shen, H. C. Liu, M. R. Hao, and Tianmeng Wang
- Subjects
Physics ,Photon ,business.industry ,Terahertz radiation ,Physics::Optics ,General Physics and Astronomy ,Illuminance ,Photodetector ,Background noise ,Optics ,Optoelectronics ,Antenna (radio) ,business ,Quantum well ,Dark current - Abstract
Theoretical studies and numerical simulations on design, performance, and improvements of terahertz quantum-well photodetector (THz QWP) are presented. In the first part of this paper, we discuss the device band structure resulting from a self-consistent solution and simulation results. First, the temperature dependence of device characteristics is analyzed. Next, we deduce the condition of optimal doping concentration for maximizing dark current limited detectivity Ddet* when QWP is lightly doped. Accordingly, unlike in previously published reports, doping concentration is not fixed and is selected by the above condition. In the second part of this paper, we propose two schemes for improving operation temperature. The first is to incorporate an optical antenna which focuses incident THz wave. Numerical results show that the QWP with peak frequency higher than 5.5 THz is expected to achieve background-noise-limited performance at 77 K or above when employing a 106 times enhancement antenna. The second sch...
- Published
- 2013
28. Absolute spectral characterization of silicon barrier diode: Application to soft X-ray fusion diagnostics at Tore Supra
- Author
-
P. Malard, D. Mazon, and D. Vezinet
- Subjects
Physics ,business.industry ,Detector ,Analytical chemistry ,Bremsstrahlung ,General Physics and Astronomy ,Semiconductor device ,Effective radiated power ,Tore Supra ,Optics ,Calibration ,Plasma diagnostics ,business ,Diode - Abstract
This paper presents an experimental protocol for absolute calibration of photo-detectors. Spectral characterization is achieved by a methodology that unlike the usual line emissions-based method, hinges on the Bremsstrahlung radiation of a Soft X-Ray (SXR) tube only. Although the proposed methodology can be applied virtually to any detector, the application presented in this paper is based on Tore Supra's SXR diagnostics, which uses Silicon Surface Barrier Diodes. The spectral response of these n-p junctions had previously been estimated on a purely empirical basis. This time, a series of second-order effects, like the spatial distribution of the source radiated power or multi-channel analyser non linearity, are taken into account to achieve accurate measurements. Consequently, a parameterised physical model is fitted to experimental results and the existence of an unexpected dead layer (at least 5 μm thick) is evidenced. This contribution also echoes a more general on-going effort in favour of long-term quality of passive radiation measurements on Tokamaks.
- Published
- 2013
29. On the lifetime of plasmonic transducers in heat assisted magnetic recording
- Author
-
Bair V. Budaev and David B. Bogy
- Subjects
Physics ,business.industry ,Numerical analysis ,Acoustics ,General Physics and Astronomy ,Near and far field ,Power (physics) ,Numerical integration ,symbols.namesake ,Transducer ,Optics ,Maxwell's equations ,Heat-assisted magnetic recording ,symbols ,business ,Plasmon - Abstract
For a heat assisted magnetic recording system to be successful, it must deliver heat to a small spot on a magnetic disk without being damaged by the applied power. This paper shows that such conditions may not be easily attained in systems that use laser energy and plasmonic near field transducers. It is also shown that the analysis and design of the near field transducers cannot rely on numerical integration of the conventional Maxwell equations of electrodynamics of continuous media, because such equations implicitly incorporate numerous assumptions that are not valid in nanoscale systems. Here, we examine assumptions inherent in the derivation of these equations and point out which assumptions are violated if they are applied to the metallic nanoscale elements of heat assisted magnetic recording systems. The main body of the paper focuses on the well-known experimental results that support our conclusions while the derivations are relegated to the appendices.
- Published
- 2012
30. Simulations of the effect of waveguide cross-section on quantum dot–plasmon coupling
- Author
-
Kristy C. Vernon, Nora Tischler, Daniel E. Gómez, and Timothy J. Davis
- Subjects
Physics ,business.industry ,Nanophotonics ,Nanowire ,Physics::Optics ,General Physics and Astronomy ,Condensed Matter::Mesoscopic Systems and Quantum Hall Effect ,Waveguide (optics) ,Optics ,Nanoelectronics ,Quantum dot ,Optoelectronics ,Spontaneous emission ,business ,Nonlinear Sciences::Pattern Formation and Solitons ,Quantum ,Plasmon - Abstract
Quantum dot–plasmon waveguide systems are of interest for the active control of plasmon propagation, and consequently, the development of active nanophotonic devices such as nano-sized optical transistors. This paper is concerned with how varying aspect ratio of the waveguide cross-section affects the quantum dot–plasmon coupling. We compare a stripe waveguide with an equivalent nanowire, illustrating that both waveguides have a similar coupling strength to a nearby quantum dot for small waveguide cross-section, thereby indicating that stripe lithographic waveguides have strong potential use in quantum dot–plasmon waveguide systems. We also demonstrate that changing the aspect ratio of both stripe and wire waveguides can increase the spontaneous emission rate of the quantum dot into the plasmon mode, by up to a factor of five. The results of this paper will contribute to the optimisation of quantum dot–plasmon waveguide systems and help pave the way for the development of active nanophotonics devices.
- Published
- 2011
31. Preface to ISIF 2009 Special Issue of Journal of Applied Physics: Science and Technology of Integrated Functionalities
- Author
-
Sandwip Dey, Carlos A. Paz de Araujo, and Orlando Auciello
- Subjects
Physics ,Ubiquitous computing ,Multimedia ,business.industry ,General Physics and Astronomy ,High density ,Nanotechnology ,computer.software_genre ,Non-volatile memory ,Magnetic memory ,Ferroelectric thin films ,Smart card ,Session (computer science) ,Architecture ,business ,computer - Abstract
The science and technology of ferroelectric thin films and their applications have attracted many researchers and experienced tremendous progress in the past 20 years. The recent worldwide increase in commercial applications of ferroelectric devices such as smart cards based on nonvolatile ferroelectric random access memories is a symbol of both the maturity and the acceptance of the technology. The 21st International Symposium on Integrated Ferroelectrics (ISIF 2009), held on September 22 to October 2, 2009 in Colorado Springs, CO, provided a forum for the academic and national laboratories research community and industry to present and share their new findings, achievements, and opinions on integrated ferroelectrics and their applications. The International Symposium on Integrated Ferroelectrics hosted the ISIF 2009. This was the first year where the ISIF held the conference in its new format under the name of International Symposium on Integrated Functionalities. The General Chairs of the ISIF in consultation with the Advisory Board and the ISIF community decided to revise the focus of the conference in order to broaden the scope to the science and technology of multifunctional materials and devices. This decision was taken in view that a new paradigm in materials, materials integration, and devices is emergingmore » with a view to the development of a new generation of micro- and nanoscale multifunctional devices. The program included three plenary presentations on diverse topics such as 'The Role of Nonvolatile Memory in Ubiquitous Computing,' 'Ferroelectrics and High Density Memory Technology,' 'Nanoscale Ferroelectrics and Interfaces: Size Effects,' four tutorial lectures on diverse topics, such as 'Magnetic Memory Applications,' 'Ferroelectrics and Ferroelectric Devices,' 'Challenges for High-K Dielectrics on High Mobility Channels,' 'Solar Cell Materials,' one poster session, and eight oral sessions. Thanks to the great efforts made by the ISIF organization committee and the session chairs, the conference successfully achieved its objectives and the work presented reflected very well the most recent advances of integrated ferroelectrics and their applications, as well as advances in other areas related to the new theme of Integrated Functionalities. Many aspects of ferroelectric, piezoelectric, high-K dielectric, magnetic, and phase change materials, including the science and technology of these materials in thin film form, integration with other thin film materials (metals or oxide electrodes), and fabrication of micro- and nanostructures based on these heterostructure layers, and device architecture and physics, were addressed from the experimental point of view. Work on theory and computer simulations of the mentioned materials and devices were discussed also with a view to the promising applications to multifunctional devices. In addition, the ISIF 2009 featured discussions of alternative nonvolatile memory concepts and materials, such as phase change memories, research on multiferroics and magnetoelectric materials, ferroelectric photovoltaics, and new directions on the science of perovskites such as biomolecular/polarizable interfaces, and bio-ferroelectric and other oxide interfaces. Following the standard submission and peer review process of Journal of Applied Physics, the selected papers presented in ISIF 2009 in Colorado Springs are published in this special issue. We believe that the papers in this special issue represent the forefront contributions to ISIF 2009 in the various areas of fundamental and applied science of integrated ferroelectrics and functionalities and their applications. We would like to take this opportunity to thank the following organizations and companies for their support and sponsorship for ISIF 2009, namely: Aixact Systems GMBH, Radiant Technologies, Symetrix Corporation, and Taylor and Francis Publishers. We would also like to thank the conference and session chairs, advisory and organizing committee members for their hard work that resulted in a very successful ISIF 2009, now in its new future-looking modality of Integrated Functionalities.« less
- Published
- 2011
32. Range, resolution and power of THz systems for remote detection of concealed radioactive materials
- Author
-
Carlos Romero-Talamas, Phillip Sprangle, V.L. Granatstein, and Gregory S. Nusinovich
- Subjects
Free electron model ,Physics ,Electron density ,business.industry ,Terahertz radiation ,General Physics and Astronomy ,Electromagnetic radiation ,Particle detector ,Optics ,Ionization ,Optoelectronics ,business ,Microwave ,Power density - Abstract
This paper analyzes parameters required for realizing remote detection of a concealed source of ionizing radiation by observing the occurrence of breakdown in air by a focused wave beam. Production of free electrons and the free electron density in the absence/presence of additional sources of ionization are analyzed. The maximum electron density in the discharge and the time required for this density to return after the discharge back to its stationary level, are estimated. The optimal excess of the power density and the corresponding power level as the function of frequency are determined. It is shown that the optimal frequency of such systems ranges from 0.3 up to 0.8 THz. The paper also determines the range of such systems as the function of the source frequency and power and contains a brief analysis of available sources of microwave, millimeter-wave and THz radiation.
- Published
- 2011
33. Tunable, continuous-wave Terahertz photomixer sources and applications
- Author
-
Longze Wang, Arthur C. Gossard, Gottfried H. Döhler, Stefan Malzer, and Sascha Preu
- Subjects
Physics ,business.industry ,Terahertz radiation ,General Physics and Astronomy ,Photodiode ,law.invention ,Photomixing ,Laser linewidth ,Optical Carrier transmission rates ,law ,Optoelectronics ,Continuous wave ,Radio frequency ,Antenna (radio) ,business - Abstract
This review is focused on the latest developments in continuous-wave (CW) photomixing for Terahertz (THz) generation. The first part of the paper explains the limiting factors for operation at high frequencies ∼ 1 THz, namely transit time or lifetime roll-off, antenna (R)-device (C) RC roll-off, current screening and blocking, and heat dissipation. We will present various realizations of both photoconductive and p-i-n diode–based photomixers to overcome these limitations, including perspectives on novel materials for high-power photomixers operating at telecom wavelengths (1550 nm). In addition to the classical approach of feeding current originating from a small semiconductor photomixer device to an antenna (antenna-based emitter, AE), an antennaless approach in which the active area itself radiates (large area emitter, LAE) is discussed in detail. Although we focus on CW photomixing, we briefly discuss recent results for LAEs under pulsed conditions. Record power levels of 1.5 mW average power and conversion efficiencies as high as 2 × 10−3 have been reached, about 2 orders of magnitude higher than those obtained with CW antenna-based emitters. The second part of the paper is devoted to applications for CW photomixers. We begin with a discussion of the development of novel THz optics. Special attention is paid to experiments exploiting the long coherence length of CW photomixers for coherent emission and detection of THz arrays. The long coherence length comes with an unprecedented narrow linewidth. This is of particular interest for spectroscopic applications, the field in which THz research has perhaps the highest impact. We point out that CW spectroscopy systems may potentially be more compact, cheaper, and more accurate than conventional pulsed systems. These features are attributed to telecom-wavelength compatibility, to excellent frequency resolution, and to their huge spectral density. The paper concludes with prototype experiments of THz wireless LAN applications. For future telecommunication systems, the limited bandwidth of photodiodes is inadequate for further upshifting carrier frequencies. This, however, will soon be required for increased data throughput. The implementation of telecom-wavelength compatible photomixing diodes for down-conversion of an optical carrier signal to a (sub-)THz RF signal will be required.
- Published
- 2011
34. Shear acoustic waves polarized along the ridged surface of an isotropic solid plate: Mode coupling effects due to the shape profile
- Author
-
Catherine Potel, Michel Bruneau, and Tony Valier-Brasier
- Subjects
Physics ,Condensed matter physics ,Scattering ,business.industry ,General Physics and Astronomy ,Acoustic wave ,Surface finish ,Ion acoustic wave ,Optics ,Mode coupling ,Isotropic solid ,Perpendicular ,Boundary value problem ,business - Abstract
The aim of the paper is to describe the modes coupling due to scattering on small one-dimensional irregularities (parallel ridges) of the surface of isotropic solid plates, when shear horizontal waves (SH-waves) polarized along the ridges propagate perpendicularly to them. In a previous paper [Valier-Brasier et al., Appl. Phys. Lett. 93, 164101 (2008)], an analytical model was presented for describing the roughness by inertia of “teeth” which bound the ridges, through an impedancelike boundary condition, whatever shape of the roughness is. In the present paper, this shape is accounted for through a more sophisticated model, used previously for describing the effects of the roughness of walls on acoustic pressure fields in fluid-filled waveguides [Valier-Brasier et al., J. Appl. Phys. 106, 034913 (2009)], and adapted here in order to describe the modes coupling due to the scattering of these SH-waves. Moreover, the effect of a spatial periodicity of the ridges on the modes coupling is discussed, emphasizin...
- Published
- 2010
35. Loss compensation in external cloaks using a thin layer of gain media
- Author
-
Wei Xiang Jiang, Hui Yuan Dong, Jin Wang, and Tie Jun Cui
- Subjects
Lossless compression ,Physics ,Optics ,business.industry ,General Physics and Astronomy ,Metamaterial ,Cloaking ,Theories of cloaking ,Lossy compression ,business ,Cloaking device ,Bipolar coordinates ,Compensation (engineering) - Abstract
Transformation optical devices based on the concept of complementary medium have attracted much attention due to their novel properties. A recent paper [H. Chen and C. T. Chan, Opt. Lett. 34, 2649 (2009)] showed a class of complementary medium in bipolar coordinates, which can render the object invisible at a distance. The prescription requires lossless materials composed of negative index medium (NIM), and a certain loss will cut off the cloaking effect of the device. In this paper, we suggest compensation to the lossy NIM by introducing gain media into such a device. For the realization of the whole cloaking device, we present an optimized compensation method to upgrade the function by adding a very thin layer of gain media in the surrounding medium. Numerical simulations demonstrate a dramatic improvement in the cloaking performance when the NIM is lossy.
- Published
- 2010
36. Evanescent modes in sonic crystals: Complex dispersion relation and supercell approximation
- Author
-
Romero García, Vicente, Sánchez Pérez, Juan Vicente, and García Raffi, Luis Miguel
- Subjects
Physics ,Condensed matter physics ,Band gap ,business.industry ,General Physics and Astronomy ,Function (mathematics) ,Finite element method ,Matrix (mathematics) ,Optics ,FISICA APLICADA ,Vacancy defect ,Dispersion relation ,Supercell (crystal) ,Plane wave expansion ,MATEMATICA APLICADA ,business - Abstract
Evanescent modes in complete sonic crystals (SCs) and SC with point defects are reported both theoretically and experimentally in this paper. Plane wave expansion (PWE) and in general, ω(k)ω(k) methods have been used to calculate band structures showing gaps that have been interpreted as ranges of frequencies where no real kk exists. In this work, we extend PWE to solve the complex k(ω)k(ω) problem applied to SC, introducing the supercell approximation for studying one vacancy. Explicit matrix formulation of the equations is given. This k(ω)k(ω) method enables the calculation of complex band structures, as well as enabling an analysis of the propagating modes related with real values of the function k(ω)k(ω), and the evanescent modes related with imaginary values of k(ω)k(ω). This paper shows theoretical results and experimental evidences of the evanescent behavior of modes inside the SC band gap. Experimental data and numerical results using the finite elements method are in very good agreement with the predictions obtained using the k(ω)k(ω) method., The authors would like to thank Dr. E. A. Sanchez-Perez for his comments and suggestions and thank Daniel Fenollosa and Talleres Ferriols for their help in building the mechanical part of 3DReAMS. This work was supported by MEC (Spanish government) and the European Regional Development Fund, under Grant Nos. MAT2009-09438 and MTM2009-14483-C02-02.
- Published
- 2010
37. Refractive error correction for in situ curvature measurement using laser beam deflection method
- Author
-
Xinran Xiao and Daniel Schleh
- Subjects
Physics ,Beam diameter ,Conjugate beam method ,business.industry ,General Physics and Astronomy ,Curvature ,Optics ,Bending stiffness ,Physics::Accelerator Physics ,Light beam ,M squared ,Laser beam quality ,Direct integration of a beam ,business - Abstract
Stoney’s equation allows one to calculate the internal stress in a thin film deposited on a thick substrate from the curvature of the bilayer beam. The curvature measurement is thus critical in the bending beam method, which is based on this equation. When an optical technique is used in curvature measurement, the refraction at optical boundaries needs to be corrected. An approximate correction to Stoney’s equation accounting for refractive error in the bending beam method in electrochemical applications was reported previously. This paper revisits the derivation. A set of diagrams for optical paths in in situ curvature measurement using the laser beam deflection method are presented. These diagrams allow us to establish the triangular relationships among the incident angles of the light beam and the deflection angle of the cantilever beam. Correction solutions are derived for three possible optical arrangements with the consideration of the travel distance of the light beam in liquid and in the container wall. In its approximated form, the correction derived in this paper differs from the previous formula by a factor of 2. It was discovered that an incorrect relationship for curvature was used in the previous derivation.
- Published
- 2010
38. Efficiency enhancement in seeded and self-amplified spontaneous emission free-electron lasers by means of a tapered wiggler
- Author
-
H. P. Freund and W. H. Miner
- Subjects
Physics ,business.industry ,Wiggler ,Self-amplified spontaneous emission ,General Physics and Astronomy ,Superradiance ,Laser ,law.invention ,Optics ,law ,Phase noise ,Physics::Accelerator Physics ,Spontaneous emission ,Stimulated emission ,business ,Noise (radio) - Abstract
The enhancement of the efficiency in free-electron lasers (FELs) through the use of a tapered wiggler is well known. The physics of the tapered wiggler interaction has been studied in theory and simulation, and large efficiency enhancements have been observed in the laboratory in oscillators and seeded amplifiers. In this paper, we study the differences in the tapered wiggler interaction between seeded amplifiers and in FELs that start up from noise and grow to saturation in a single pass through the wiggler. This configuration is commonly referred to as self-amplified spontaneous emission (SASE). In comparison with seeded amplifiers, SASE FELs exhibit shot-to-shot fluctuations due to random phase noise in the electron bunches, and our purpose in this paper is to determine the effect of this phase noise on the tapered wiggler interaction. To this end, we study the interaction numerically using the MEDUSA simulation code for seeded and SASE FELs operating in the infrared regime. The results of the simulati...
- Published
- 2009
39. Electronic and optical properties of InGaN quantum dot based light emitters for solid state lighting
- Author
-
Hung-Hsun Huang, Yih-Yin Lin, Yuh-Renn Wu, and Jasprit Singh
- Subjects
Physics ,business.industry ,Wide-bandgap semiconductor ,General Physics and Astronomy ,Condensed Matter::Mesoscopic Systems and Quantum Hall Effect ,law.invention ,Solid-state lighting ,Optics ,law ,Quantum dot laser ,Quantum dot ,Optoelectronics ,Emission spectrum ,Electronic band structure ,business ,Quantum well ,Light-emitting diode - Abstract
In this paper, we have made a systematic study of the electronic and optical properties of InGaN based quantum dot light emitters. The valence force field model and 6×6k⋅p method have been applied to study the band structures in InGaN or InN quantum dot devices. Piezoelectric and spontaneous polarization effects are included. A comparison with InGaN quantum wells shows that InGaN quantum dots can provide better electron-hole overlap and reduce radiative lifetime. We also find that variation in dot sizes can lead to emission spectrum that can cover the whole visible light range. For high carrier density injection conditions, a self-consistent method for solving quantum dot devices is applied for better estimation of device performance. Consequences of variations in dot sizes, shapes, and composition have been studied in this paper. The results suggest that InGaN quantum dots would have superior performance in white light emitters.
- Published
- 2009
40. Tunable topological valley Hall edge state based on large optical Kerr effect
- Author
-
Keya Zhou, Kai Guo, Shutian Liu, Zhongyi Guo, Fujia Chen, and Qingsong Xue
- Subjects
Path (topology) ,Physics ,Kerr effect ,business.industry ,Point reflection ,Physics::Optics ,General Physics and Astronomy ,Edge (geometry) ,Condensed Matter::Mesoscopic Systems and Quantum Hall Effect ,Topology ,Transmission (telecommunications) ,Topological order ,Photonics ,business ,Intensity (heat transfer) - Abstract
Most of the photonic valley-Hall edge states were constructed by changing structures to break the spatial inversion symmetry, restricting the practical application potential. In this paper, we construct a tunable topological valley-Hall edge state based on the large optical Kerr effect. It is demonstrated that topological phase transition happens by engineering the intensity of the injected pump and that a valley-Hall edge state can be generated at the interface between two regions with different topological properties. In addition, eigenfrequency and transmission characteristics of the edge state as a function of applied pump intensity are investigated. The topological protected valley-dependent transmission is studied under non-uniform distributed pump intensity. This work may open a new path toward designing reconfigurable all-optical metadevices.
- Published
- 2021
41. Transverse magnetic modes of localized spoof surface plasmons
- Author
-
Chao-Hai Du, Si-Qi Li, Feng-Yuan Han, Pu-Kun Liu, Yi-Dong Wang, Yunhua Tan, and Zi-Chao Gao
- Subjects
Electromagnetic field ,Physics ,Resonator ,Optics ,business.industry ,Electric field ,Surface plasmon ,Plane wave ,General Physics and Astronomy ,Grating ,business ,Transverse mode ,Magnetic field - Abstract
Electric and magnetic modes establish the basis of the localized spoof surface plasmons (LSSPs), both of which are transverse electric (TE) modes. In this paper, the concept of transverse magnetic (TM) modes of LSSPs is proposed, and the double-layer planar-circular-grating resonator is demonstrated to support the TM modes in addition to the TE modes. In numerical simulations, the TE and TM modes were excited by a plane wave and an aperture, respectively, and their resonant frequencies and electromagnetic field distributions were demonstrated to be different. The electric field of the TE mode is parallel to the grating, while the magnetic field of the TM mode is parallel to the grating. In experiments, multiple TE and TM LSSPs modes were excited by a magnetic coupler. The magnetic coupler can be rotated to distinguish the TM modes from the TE ones, which provides conclusive evidence of the existence of the TM modes. Compared with the TE LSSPs modes, the TM LSSPs modes have the advantages of high sensitivity to the distance between layers and high quality factors (Q-factors), which hold promise for providing improvements on compact applications of LSSPs. Based on the proposed concept, therefore, the classification standard of the LSSPs is expanded to make it more scientific and comprehensive.
- Published
- 2021
42. A scattering and absorption identity for metamaterials: Experimental results and comparison with theory
- Author
-
Christian Sohl, Mats Gustafsson, Christer Larsson, and Gerhard Kristensson
- Subjects
Physics ,Scattering ,business.industry ,General Physics and Astronomy ,Metamaterial ,Optical theorem ,Computational physics ,Bistatic radar ,Cross section (physics) ,Optics ,Extinction (optical mineralogy) ,Dispersion relation ,Sum rule in quantum mechanics ,business - Abstract
A dispersion relation for the combined effect of scattering and absorption of electromagnetic waves is presented for a large class of linear and passive material models. By invoking the optical theorem, the result states that the extinction cross section integrated over all frequencies is equal to the static limit of the extinction volume. The present paper focuses on an attempt to experimentally verify this sum rule by measuring the monostatic radar cross section of a fabricated sample of metamaterial. In particular, the paper utilizes the idea that, for a specific class of targets, the scattered fields in the forward and backward directions are identical. It is concluded that the theoretical findings are in good agreement with measurements performed in the frequency range [3.2,19.5] GHz.
- Published
- 2008
43. Microscale temperature measurement by the multispectral and statistic method in the ultraviolet-visible wavelengths
- Author
-
Benjamin Remy, Thomas Pierre, and Alain Degiovanni
- Subjects
Physics ,Optics ,business.industry ,Thermal radiation ,Multispectral image ,Emissivity ,General Physics and Astronomy ,Flux ,Black-body radiation ,Photonics ,business ,Temperature measurement ,Microscale chemistry - Abstract
The aim of this paper is to present a nonintrusive and optical method based on the classical thermal radiation laws for the measurement of microscale surface temperature. To overcome the diffraction limit, measurements are performed in the ultraviolet-visible range. According to the Planck’s law, emitting energy is low at these wavelengths and only a photonic flux can be measured through a cooled photomultiplier tube and a photon-counting card. The photonic flux exhibits a random character that can be described through well-known statistic laws such as Poisson or normal distributions. It is shown in this paper that the measured signal (photonic flux) agrees well with these statistics laws and that the surface temperature can be obtained either from the average or/and the standard deviation of the photonic flux. A multispectral technique is also introduced to get rid of the knowledge of the local surface emissivity, which is of particular interest for the measurement of temperature in microscale applications. Finally, temperature measurements carried out on a specific high temperature blackbody developed in our laboratory are compared with those obtained through an infrared camera and allow us to validate our facility and the proposed measurement technique.
- Published
- 2008
44. Controllable probe absorption spectrum via vortex beams excitation in a cascaded atomic system
- Author
-
Chen Peng, Chunling Ding, Rui-Bo Jin, Xiangying Hao, and Xiao Dai
- Subjects
010302 applied physics ,Physics ,Angular momentum ,Absorption spectroscopy ,business.industry ,Electromagnetically induced transparency ,General Physics and Astronomy ,Resonance ,02 engineering and technology ,021001 nanoscience & nanotechnology ,01 natural sciences ,Optical switch ,Optics ,0103 physical sciences ,0210 nano-technology ,business ,Absorption (electromagnetic radiation) ,Optical vortex ,Excitation - Abstract
Dynamic control of probe absorption spectrum via vortex beams in multilevel systems has attracted much attention because it provides an avenue to observe unique transport properties. In this paper, we employ experimentally accessible parameters to flexibly control the probe absorption spectrum that shows vortex-induced transparency (VIT) and absorption (VIA) phenomena. Specifically, this system can be served as an optical switch while the vortex beams can act as the control knob, which has the ability to switch from a transparency dip to an absorption peak. Differing from a conventional electromagnetically induced transparency technique, our proposed scheme investigates VIT and VIA by tuning the orbital angular momentum of vortex beams in the resonance and non-resonance cases. Moreover, the collective feature caused by constructive or destructive interference is also studied via adjustable frequency detuning. Our results may provide an efficient approach to study similar phenomena in multilevel quantum systems driven by optical vortex beams.
- Published
- 2021
45. A metamaterial lens based on transformation optics for horizontal radiation of OAM vortex waves
- Author
-
Shah Nawaz Burokur, Haoxiang Sun, Chenchen Liu, Die Li, Zhe Shi, Lina Zhu, Xiaoming Chen, and Jianjia Yi
- Subjects
010302 applied physics ,Physics ,business.industry ,Physics::Optics ,General Physics and Astronomy ,Metamaterial ,02 engineering and technology ,021001 nanoscience & nanotechnology ,01 natural sciences ,Electromagnetic radiation ,Vortex ,law.invention ,Lens (optics) ,Optics ,law ,0103 physical sciences ,Antenna (radio) ,0210 nano-technology ,Omnidirectional antenna ,business ,Microwave ,Transformation optics - Abstract
Vortex electromagnetic waves carrying orbital angular momentum (OAM) have been widely discussed for potential applications in wireless communications. Belonging to the Laguerre–Gaussian beams family, such type of waves present a hollow conical shape and divergence characteristics along with a directional radiation. In this paper, an innovative method to produce omnidirectional OAM beams based on spatial transformation is proposed at microwave frequencies. As a proof-of-concept demonstration, a lens with omnidirectional radiation in the horizontal plane is designed and simulated with an incident vortex beam carrying the OAM mode l = +2. The designed lens can be potentially implemented with an all-dielectric medium showing a gradient permittivity distribution. Furthermore, the proposed lens presents good performances over a wide operational bandwidth spanning from 8 to 17 GHz. By converting the directional beam to an omnidirectional one, the proposed method opens the door to the potential development of microwave vortex antenna systems.
- Published
- 2021
46. Magnetization dynamics of a flux control device fabricated in the write gap of a hard-disk-drive write head for high-density recording
- Author
-
Naoyuki Narita, Hitoshi Iwasaki, Tazumi Nagasawa, Gaku Koizumi, Hirofumi Suto, Tomoyuki Maeda, Masayuki Takagishi, and Akihiko Takeo
- Subjects
010302 applied physics ,Physics ,Magnetization dynamics ,Field (physics) ,business.industry ,General Physics and Astronomy ,Biasing ,02 engineering and technology ,021001 nanoscience & nanotechnology ,01 natural sciences ,Flux control ,Magnetization ,Amplitude ,0103 physical sciences ,Head (vessel) ,Optoelectronics ,Torque ,0210 nano-technology ,business - Abstract
The design concept of microwave-assisted magnetic recording (MAMR) using the flux control (FC) effect has been proposed as a technology for hard disk drives (HDDs). In this type of MAMR, the magnetization of an in-gap device (FC device) is reversed against the gap field by spin-transfer torque, enhancing the amplitude and gradient of the recording field. In this paper, we study the magnetization dynamics of an FC device fabricated in the write gap of an HDD write head. The operation of the FC device is analyzed by measuring the temporal resistance change in the sub-nanosecond region. Reversal of the FC device becomes faster as the bias current is increased and can be completed by 0.5 ns after the transition of the write current. The experimental results are reproduced by micromagnetic simulations using a head model, confirming that the simulations correctly describe the magnetization dynamics of the actual device. The simulations show that the recording field gain by the FC device appears with little delay after the rise of the recording field and that the FC device operates effectively even at a fast write rate of approximately 3 Gbit/s. Furthermore, we demonstrate the effectiveness of boosting the bias current, which can realize both fast and reliable operation of the FC device. These results indicate that the FC device operates as designed and that MAMR using the FC effect is promising for extending the recording density of HDDs.
- Published
- 2021
47. Ultra-low field frequency-swept electrically detected magnetic resonance
- Author
-
James P. Ashton, W. R. Barker, Brian R. Manning, and Patrick M. Lenahan
- Subjects
010302 applied physics ,Physics ,Spectrometer ,Magnetoresistance ,Field (physics) ,business.industry ,Transistor ,General Physics and Astronomy ,02 engineering and technology ,021001 nanoscience & nanotechnology ,01 natural sciences ,law.invention ,Magnetic field ,Laser linewidth ,Coupling (physics) ,Interference (communication) ,law ,0103 physical sciences ,Optoelectronics ,0210 nano-technology ,business - Abstract
We have developed a new ultra-low field frequency-swept (FS) electrically detected magnetic resonance (EDMR) spectrometer to perform sensitive EDMR measurements of 4H-silicon carbide (SiC) metal–oxide–semiconductor field-effect transistors at sub-millitesla (mT) magnetic fields. The new spectrometer design enables the detection of so-called ultra-strong coupling effects such as multiple-photon transitions and Bloch–Siegert shifts. In this paper, we present a new spectrometer design and discuss ultra-low field FS-EDMR sensitivity to both multiphoton transitions and Bloch–Siegert shifts of the FS-EDMR response. FS-EDMR effectively eliminates the interference of the sub-mT EDMR response from a near-zero field magnetoresistance (NZFMR) phenomenon that pervades the sub-mT regime in a magnetic field-swept EDMR scheme. We discuss an automatic power leveling scheme, which enables frequency sweeping. We also present results illustrating the Bloch–Siegert shift of the FS-EDMR response. Finally, we study the two-photon transition line shape in the 4H-SiC transistor as a function of the static field, in which we observe a collapse of the two-photon linewidth with decreasing static field and compare our results to the theory of two-photon absorption in EDMR.
- Published
- 2021
48. Dual-band reflection polarization converter for circularly polarized waves based on a zigzag asymmetric split ring resonator
- Author
-
Shengyuan Shi, Kefang Qian, Jianfeng Dong, Min-Hua Li, Jing Dai, and Wentao Gao
- Subjects
010302 applied physics ,Physics ,business.industry ,General Physics and Astronomy ,Resonance ,02 engineering and technology ,021001 nanoscience & nanotechnology ,Polarization (waves) ,01 natural sciences ,Standing wave ,Split-ring resonator ,Optics ,Zigzag ,0103 physical sciences ,Reflection (physics) ,Equivalent circuit ,Multi-band device ,0210 nano-technology ,business - Abstract
Polarization converters based on metasurfaces are one of the recently developed metadevices that can change the polarization state with designated modes, utilizing the sub-wavelength unit construction. In this paper, a kind of planar zigzag asymmetric split ring resonator (Z-ASRR) metasurface with dual bands is proposed to achieve nearly perfect polarization conversion for circularly polarized waves. Compared with the original prototype asymmetric resonant ring (ASRR), both magnitude and bandwidth have been remarkably improved for achieving a higher resonance, with the introduction of zigzag metallic wires. The reflection polarization conversion ratio possesses two peak values with 0.94 and 0.99 at 5.39 GHz and 9.65 GHz, respectively. It is also demonstrated that the introduction of extra gaps, which are closely linked with the multi-node standing wave characteristic, can control the number of resonant modes or modulate the relative bandwidth. Besides, an equivalent circuit model, the degree of zigzag bending, and the oblique incidence are further analyzed in detail. The experimental results agree well with the simulations, and this chiral metadevice could be applied for on-chip integration in an optical detection/laser, a chiral biosensor, and molecular spectroscopy.
- Published
- 2021
49. Polarization transfer from a laser to x rays via Thomson scattering with relativistic electrons: A dipole radiation perspective
- Author
-
Zhijun Chi
- Subjects
010302 applied physics ,Physics ,Thomson scattering ,business.industry ,Linear polarization ,Astrophysics::High Energy Astrophysical Phenomena ,General Physics and Astronomy ,02 engineering and technology ,Electron ,021001 nanoscience & nanotechnology ,Laser ,Polarization (waves) ,01 natural sciences ,law.invention ,Optics ,law ,Electric field ,0103 physical sciences ,Degree of polarization ,0210 nano-technology ,business ,Circular polarization - Abstract
A Thomson scattering light source can produce polarization-controllable x rays with quasi-monochromaticity and high brightness, making it an excellent probe for x-ray imaging and nuclear physics research. In this paper, a clear physical picture of the polarization transfer process from a laser to x rays is given based on a dipole radiation model. For arbitrary interaction geometries between a laser and relativistic electrons, the electric field relation between the scattered x rays and the laser is derived analytically. The result shows that the polarization characteristics of the laser can be completely transferred into x rays, regardless of the interaction geometry. Meanwhile, the polarization of scattered x rays is dependent on the collecting angle. As the collecting angle increases, both the degree of polarization (DOP) and the bandwidth of scattered x rays will be degraded. A collecting angle confining scattered x rays of 5 % rms bandwidth can guarantee a DOP higher than 97 % for both linear and circular polarizations. A method for any polarization control of scattered x rays is demonstrated by using wave plates for the laser. Both the rotation of linear polarization and the switch of polarization state from linear polarization to circular polarization and from left-handed polarization to right-handed polarization can be easily realized.
- Published
- 2020
50. Testing the quantization of electromagnetic field in a quarter-wavelength transmission line resonator by traveling-wave scattering measurements
- Author
-
Jiansong Gao, Lianfu Wei, Gao Haiyan, and Donghai Zhai
- Subjects
010302 applied physics ,Electromagnetic field ,Physics ,Photon ,Scattering ,business.industry ,Physics::Optics ,General Physics and Astronomy ,02 engineering and technology ,021001 nanoscience & nanotechnology ,01 natural sciences ,Quantization of the electromagnetic field ,Transmission line resonator ,Wavelength ,Quantization (physics) ,Optics ,0103 physical sciences ,Quantum system ,0210 nano-technology ,business - Abstract
A half-wavelength cavity, wherein the electromagnetic field is quantized as standing-wave photons, is a typical artificial quantum system that has widely been used to implement quantum information processing. In this paper, we propose an approach to confirm the quantization of the electromagnetic field in another type of cavity, namely, a quarter-wavelength transmission line resonator (TLR), by using traveling-photon scattering measurements. Furthermore, we show that the number of photons in a TLR can be destructively detected by using the usual IQ-mixed technique. We hope that quarter-wavelength TLRs may also serve as quantum devices to implement on-chip solid-state quantum information processing.
- Published
- 2020
Discovery Service for Jio Institute Digital Library
For full access to our library's resources, please sign in.