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The dispersive wave emission can be enhanced and blue-shifted by selectively exciting high-order-modes (HOMs) in gas-filled hollow-core anti-resonant fiber pumping at 1030 nm with pulses of 30 fs duration and $12\ \mu \mathrm{J}$ energy. Multi-octave supercontinuum spanning 200–1400 nm has been demonstrated by exciting LP02 mode. © 2021 The Author(s)

Terahertz (THz) spectra encode information on charge transport on nanoscale distances. The linear response thus provides information on charge transport in weak electric fields. Existing theoretical models range from numerical Monte-Carlo calculations [1] or analytical calculations based on diffusion [2] to quantum-mechanical approaches [3] . Although still not fully understood, there is nowadays a clear picture of the linear terahertz conductivity in semiconductor nanostructures [4] . Recent developments of sources of intense terahertz radiation open an immense field of experimental high-field physics [5] . This allowed a great progress in the understanding of high-field response namely in bulk semiconductors [6] . However, very little is still known about the nonlinear terahertz response of semiconductor nanostructures, either from experiments or from theory.

π -conjugated semiconducting polymers have the potential to provide low cost, flexible and thin optoelectronic devices such as light-emitting diodes, field effect transistors and solar cells. The ultrafast dynamics of tightly bound, Frenkel excitons in these materials are crucial for the performance of these devices [1] , [2] . In this work we demonstrate the first application of soft X-ray transient absorption spectroscopy to study exciton dynamics in an organic semiconducting polymer, poly(3-hexylthiophene) (P3HT). The samples are pumped with a ∼ 15 fs optical pulse resonant with the π → π * transition at 2.25 eV, relevant to solar energy conversion. The probe is a soft X-ray supercontinuum extending to 350 eV with attosecond pulse duration generated via high harmonic generation [3] . Figure 1a shows the transient absorption spectrum of P3HT in the vicinity of the carbon K edge. At all positive time delays a blue shift in the absorption edge is observed giving rise to the strong increase in absorption at 286.25 eV. At short time delays this is accompanied by a weaker positive differential absorption feature 1.2 eV below the edge. The low energy feature is highly transient and decays with a lifetime of 16 8 fs. With the support of TDDFT simulations ( Fig. 1b ), we associate the spectral blue shift with the localised ± singlet exciton and the low energy transient feature as a direct spectroscopic signature of delocalisation of the exciton between polymer chains. Our results suggest that the photoexcited H-aggregate type state undergoes rapid localisation on a sub 50 fs timescale consistent with theoretical predictions for this polymer [4] .

In this paper, the finite element method is used to calculate the extinction optical properties and electric field distribution of gold core silver shell nanorod-gold film nanostructures. The volume ratio of silver and the length diameter ratio of core-shell nanorods can be changed by controlling the thickness of silver layer, which can realize the regulation of the longitudinal mode peak position from 600 to 900 nm. The electric field intensity of the core-shell nanorod-gold film structure increases with the increase of the volume ratio of silver. Silver is the plasmon material with the smallest loss in the visible light region, due to its small imaginary part of the dielectric function and lower plasma damping than gold. Therefore, with the increase of the volume ratio of silver, the extinction spectrum intensity of the gold core silver shell nanorod-gold film increases obviously, and the blue shift of the peak position and the narrowing of the full width at half maximum of the wave shape are obvious changes. At the same time, the structure gap confines the light to the deep sub wavelength range, which will produce a hot spot in the gap, which will enhance the electric field.

In this work, many-body effects including band-gap renormalization (BGR), Coulomb enhancement (CE) and carrier collisions (CS) are considered when the micro light emitting diode (micro-LED) operates in the injection level above 100 kA/cm2. Electroluminescence (EL) spectra of 20 micron-diameter LEDs show the redshift and broadening with current density increasing from 50 to 360 kA/cm2. An abnormal increases of external quantum efficiency (EQE) are observed above 100 kA/cm2. BGR effect combined with thermal effect lead to redshift of EL peak wavelength. Carriers collision dominates spectral width. CE enhances radiative recombination and also results in blue shift of peak wavelength.

$\beta$ -As 2 Te 3 which is isostructural to topological insulator Bi 2 Te 3 , has been doped with copper in order to investigate the effect of the addition of charge carriers on the optical properties and electronic structure. The plasma edge in the MIR reflectance undergoes a blue shift to higher energy with increasing copper. The Drude fit parameters suggest that distinct mechanisms may exist for the doping in different regimes.

In this paper, we report the largest bandgap blueshift of 320meV (~105nm) novel quantum well intermixing (QWI) technique in the InGaP/AlInGaP single quantum-well laser structure. We applied external compressive strain using a thick SiO 2 cap with a thickness ≥ of 1000 nm, annealed at 950°C for the number of cycles from 30-240s of annealing duration to enhance the QWI process. Using this method, wavelength tunability over a range of 640nm to 545nm ( 320meV) was demonstrated. The emission around ~545nm is the first demonstration of the photoluminescence in the green emission region on InGaP/InAlGaP QW structures.

The correlated color temperature (CCT) shift after the polymer curing process is a very common phenomenon in Light Emitting Diodes (LEDs) packaging. During the curing process, the particles in LED encapsulant will flow with the fluid due to the nonuniform heating inside the polymer. Then, the polymer and the phosphor particles will solidify very quickly when the cross-linking reaction is trigged. In order to investigate the difference of the phosphor positions before and after the curing, in this work, a finite element analysis (FEA) simulation was carried out to simulate the flow of the polymer that contained the phosphors. The light color performance was subsequently simulated by finite-difference time-domain (FDTD) and Ray tracing (RT) combined method. As the result shows, the flow of LED encapsulant with phosphor particles can change the concentration of phosphor in different layers of LED encapsulant. Such changes can cause redshift and blueshift of transmitted light. Finally, new structure encapsulation cups were proposed to inhibit the flow of LED encapsulant with phosphor particles. The results shows that the serrated encapsulation cup can effectively inhibit the change of concentration during LED encapsulant curing.

Photoluminescence (PL) and Raman studies were carried out to investigate the effect of growth rate on $\mathrm{GaAs}_{1-\mathrm{x}}\mathrm{sBi}_{\mathrm{x}}$ alloys. The samples were grown between 0.09 and 0.5 $\mu\mathrm{m}/\mathrm{hour}$ , At room temperature, the lowest PL peak energy (1.07 eV) was obtained by sample grown at 0.23 $\mu\mathrm{m}/\mathrm{hour}$ . Samples grown at lower and higher than 0.23 $\mu\mathrm{m}/\mathrm{hour}$ showed PL peak energy redshift and blueshift, respectively. Raman data show peaks at 162, 228, 270 and 295 cm−1which correspond to the GaAs like phonons. The GaBi like phonons were also observed at 183 and 213 cm−1but their intensity are significantly weaker compared to GaAs like phonons. PL and Raman data show that Bi incorporation into GaAs lattice is dependent on the growth rate and in this study, the highest Bi concentration was obtained for sample grown at 0.23 $\mu \mathrm{m}/\mathrm{hour}$ .

The effects of Mg doping on the optical and electrical properties of solution-processed ZnO quantum dots (QDs) thin film has been analyzed. The thin film of ZnO QDs with different doping concentration of Mg (2% and 4%) are deposited over the glass substrate using solution processing. The effect of doping is evident on the bandgap of the material as the doped QDs shows blue shift in the absorption spectrum. Further, we have analyzed fabricated device of Mg-doped ZnO QD and calculated carrier concentration, Hall mobility, and sheet resistance. The values found to be 4.88x1014 cm-3, 4.92 cm2/VS, and 5.18x108 Ω/□ respectively for Mg (2%)-doped ZnO QDs and 5.39x1014 cm-3, 6.60 cm2/VS, and 5.56x108 Ω/□ respectively for Mg(4%)-doped ZnO QDs. The device with doping of 4% Mg shows the better electrical properties comparative to ZnO QDs with Mg doping of 2% and 0%. The transmittance curve of ZnO QDs shows the sharp cut-off for visible region with increase in doping percentage and Mg(4%)-doped ZnO shows ~90% transmittance across the visible region with sharp increase in 360nm. These characteristics of Mg-doped ZnO can be further utilized for photodetection application of short wavelengths.

Nonconjugated polymers have been synthesized from maleic anhydride, poly(ethylene glycol), and bisphenol-diglycidyl ether without utilizing any solvent. The polymeric thin films produced by the nonconjugated polymers were spin-coated on ITO coated glass and Si substrates. Self-assembly nanoparticles (1.6–6.2 nm) are observed. It is proposed that the nanoparticle is constructed through a self-assembly process with bisphenol-A aggregates and poly(ethylene glycol) moieties. The photoluminescence spectrum of the polymeric thin film on ITO peaks at near 450 nm that spans from 360 to 610 nm under 266 nm excitation. The polymeric thin film exhibits the excitation-wavelength-dependent photoluminescence that the emission peak shifts toward longer wavelength (about 11 nm) when the excitation wavelength increases from 266 to 325 nm, which is attributed to nanoparticle size distribution. Meanwhile, the substrate-dependent photoluminescence has been also observed that the PL peak of the polymeric thin film spin-coated on Si shows a blue shift (about 9 nm) compared with that on ITO, which probably arises from the dielectric screening. The highest occupied molecular orbital energy of the polymeric thin film is about –9.4 eV. The optical band gap is about 3.28 eV. The nonconjugated polymer is expected to use as a host material in optoelectronic applications.

This paper investigates optimization and power/wavelength allocation of a RAMAN amplifier designed for Dense Wavelength Division Multiplexed (DWDM) Systems consisting of forty channels with frequency spacing 25 GHz at the edge of L and U wavelength bands (185 THz – 185.975 THz). Four pumps used in the forward direction with wavelengths at 1500, 1525, 1565, 1574 nm and four pumps in the backward direction with wavelengths at 1435, 1460, 1474, 1489 nm are used. The forward pumps power distribution and backward pump power distribution combinations are investigated for the Raman amplifier best performance. The performance of the system includes overall gain and flatness. The location of the wavelength in the forward or backward direction and the power distribution among each wavelength in an ascending or descending order is also investigated. It is found that the red shifted pump wavelengths should be used in the forward direction and the blue shifted pump wavelengths should be used in the backward direction for best performance.

We present a single-layer H-shaped all-silicon array exhibiting tunable ultra-broadband terahertz wave absorption. Experiment and simulation reveal near unity absorption at ~1 THz, with a bandwidth of ~913 GHz for ≥90% absorbance. The absorption is optically tunable, exhibiting a resonance frequency blueshift by 420 GHz, while the peak absorbance remains over 99%. The dynamic response upon optical excitation depends upon the penetration depth of the pump beam in silicon, as demonstrated from simulation taking into account the depth dependence of the carrier concentration in the all-silicon metamaterial perfect absorber. The results unveil the tuning mechanisms in optically tunable all-silicon metamaterials and metasurfaces, guiding the development of functional all-dielectric functional terahertz devices, such as switches and modulators.

We report on the first demonstration of an anomalous blue-shift of whispering-gallery modes (WGMs) using metallic substrates. The results allow for frequency tuning of WGMs essential for numerous applications, and establish novel insights into the anomalous blue-shift of WGM cavity systems.

A fiber biosensor based on tapered singlemode-no core-singlemode (SNS) fiber structure was investigated for the detection of staphylococcus aureus. The fibre sensor was functionalised by depositing the pig IgG antibodies onto tapered biosensor surface, which has specific binding with staphylococcus aureus. The experimental results showed that transmission spectrum of functionalized sensor undergone wavelength blue shift when it was immersed into Staphylococcus aureus solution, and 1.1 nm wavelength shift was observed with a concentration of 101colony-forming units (CFU)/mL.

Nuclear radiation effects on nanostructured semiconductors are concerned for the nano-detectors in space applications. In this paper, the neutron-irradiation effects on the ZnO nanowires and nanoflakes grown by chemical vapor transportation were investigated. After 10 $^{15}$ n/cm$^{2}$ neutron irradiation, the ZnO nanowires maintained their structures with their diameter decreased, while the ZnO nanoflakes changed their structures into nanoparticles, which indicates that the ZnO nanowire structure is more stable than the nanoflake structure for the neutron irradiation. The neutron irradiation causes a red shift of the near band emission peak for the irradiated ZnO nanowires, which is probably due to the generation of shallow defects, and a blue shift for the ZnO nanoflakes, which is consistent with the structure transformation of the nanoflakes.

We create exciton-polariton (strongly coupled light-matter quasi particles) Bose-Einstein condensates at room temperature [1] by optically exciting a ladder-type conjugated polymer [2] placed inside a tuneable Fabry-Perot microcavity [3]. By Focussed Ion Beam (FIB) milling we fabricate different structure for inplane confinement, ranging from 0D (single Gaussian-shaped defect) to 2D ones (arrays of coupled Gaussian defects). In the first part of this work we focus on the basic building blocks of our system, the strong light-matter coupling and the exciton-polariton condensation localized in a 0D Gaussian-shaped defect structure. The strong coupling between the excitonic resonance of the conjugated polymer and the individual cavity modes is obtained by exciting the system while detuning the cavity length till the anti-crossing behaviour of the modes appears. By increasing the excitation power above threshold, we reach room temperature condensation in a single Gaussian defect. The condensation features are demonstrated by showing non-linear emission intensity, spectral line-narrowing and a characteristic blue shift as function of excitation power. To better characterize the condensation in such a system, we studied the angular emission (Fig. 1 (a) and (b)) and the first order coherence (Fig. 1 (c) and (d)) of the exciton-polaritons below and above threshold.

We investigated the regional control of the band-gap originated from the highly-stacked quantum dots (QD) on the InP (311)B substrate changing ion implantation depths using quantum dot intermixing (QDI) technique the QDI process involved B+ implantation and rapid thermal annealing (RTA) at 600 °C, in which the ion implantation depths were controlled regionally with a combination of SiO 2 and resist (AZ) films. Controlled blue shift of the photoluminescence (PL) spectra verified the effectiveness of the controlled QDI process for the application to semiconductor photonic integrated circuits using 1550nm-band QDs.

Cathodoluminescence (CL) spectra of rocksalt-structured (RS) Mg 0.92 Zn 0.08 O/MgO quantum wells (QWs) were measured in the VUV spectral region. Near-band-edge CL peak energies exhibited moderate blueshift by changing in the quantum well thickness. Present results demonstrate possible application of $\mathbf{RS}-\mathbf{Mg}_{\mathbf{x}}\mathbf{Zn}_{1-\mathbf{x}}\mathbf{O}/\mathbf{MgO}\ \mathbf{QWs}$ for solid-state VUV light-emitter.

Bandgap width within first Brillouin zone in metamaterial-based two-dimensional photonic crystal structure is analytically computed using plane wave expansion method. A wider range of negative refractive index is considered for simulation purpose within physically feasible limit whereas rectangular geometrical shape is taken into account for the analysis with TE mode of propagation. Artificial materials in presence of air holes are considered to achieve negative index, and results are compared with that obtained for conventional SiO 2 -air material system with equivalent dimensional configuration. Coordinates of two peak points, $\hbox{`}\Gamma\hbox{'}$ point and ‘X’, point are noted for all the DNG materials which give the indication of blueshift of the valence region with change of negative refractive index. Simulated findings speak in favor of multiple forbidden regions for some specific material systems which can be utilized to design photonic multi-channel filter in beyond THz region.

Frequency shifts of light scattered from either a deterministic or random medium have shown great importance in remote sensing imaging applications, however, such scattering system which combines random scatterer with obstacles has not been specifically discussed so far. To solve this problem, we derive analytical expressions for showing the phenomenon that the Young's pinhole wave scattered from a quasi-homogeneous (QH) medium exhibits the red shift of spectral lines, while the first-order Born approximation is applied to treat the weak scattering between the diffractive wave and the medium. The shifted amount of spectrum is strongly dependent of the scattering angle, correlation length of the medium, and Young's pinhole parameter. Furthermore, we also observe that the red shift of the scattered spectrum converts to the blue shift when the correlation length reaches a certain magnitude. Through numerical simulations, analyses are performed on revealing the effects of Young's pinhole parameter and medium's correlation on the spectral shift and spectral switch of the scattered spectrum.

A sensing fluorescent probe based on the photoluminescence (PL) quenching of the AgInS2 colloidal nanocrystals (NCs) with a wide bandgap ZnS shell was studied for nickel ions detection. Nanocrystals were synthesized in aqueous solution using mercaptopropionic acid as surfactant. Decreasing of PL intensity of the NCs AgInS2/ZnS in the presence of nickel ions was accompanied by a blueshift of maxima of PL spectra. The shift ranged from 635 to 603 nm with an increase in the concentration of nickel ions from 0 to 4×10-3 mol/L. The quenching effect was described by the Stern–Volmer relationship. The obtained results could be useful for the development of new express-methods for heavy metal detection in aqueous media.

An optical fiber sensor based on fiber Bragg grating (FBG) and Mach-Zehnder interferometer (MZI) is experimentally demonstrated for simultaneous measurement of refractive index (RI) and temperature. It features a single mode-multimode-single mode (SMS) fiber structure and a spherical-shape. The fabricated sensor exhibited sensitivities of FBG and MZI are 0.0098 nm/°C and 0.093 nm/°C, respectively. The sensor possesses the advantages of easy fabrication, good robustness and high sensitivity.

The contribution deals with investigation of photoluminescence (PL) signal recorded on the inhomogeneous porous p-type silicon. PL signal was measured in equidistant points with spacing 0.05 mm. Following parameters were evaluated: 1.) spectral dependence of PL signal and number of identified Gaussian PL peaks; 2.) positions of the peaks; 3.) intensities of peaks; 4.) half-widths (FWHM) of the peaks. PL peaks were localized in vicinity of energies 1.8 and 1.9 eV, respectively. The blue shift of positions of PL maxima was observed and related to increasing PL intensities. The peak 1.8 eV showed increase of FWHM related to increase of blue shift. The peak 1.9 eV showed slight decrease of it. This behaviour is attributed to the increase of the thickness of porous layer and it is related with structural changes. In our opinion, these effects may be related, also, with SiOxHy compounds covering the surface of the structure and their chemical changes induced by applied manufacturing technology of the porous layers.

we demonstrate a hybrid structure fabricated by depositing SiN, cylinders arrays in organic polymer film Poly [2- (2', 5" -bis (2" -ethylhexyloxy)-phenyl)-l, 4-phenylene vinylene] (BEHP-PPV). The gain emission peak is at about 518 nm, and threshold is around 3.3 mJ/cm2.

As temperature cycles between 58 °C and 72 °C, VO 2 undergoes a hysteretic transformation between the monoclinic phase and rutile phases, leading to a cyclical change in the complex refractive index that is indicative of semiconductor↔metal transitions. We simulated the visible/near-infrared spectra of the specular reflectance and transmittance of a metasurface incorporating a VO 2 sheet and found that the extrema in both spectra blueshift from the cooling to the heating phases at a fixed temperature. This phenomenon is attractive for sensing temporal gradients of temperature.

Perovskite material has found a numerous attention in the last few years due to its remarkable application’s in high efficiency photovoltaics $(\sim 21.2$%), light emitting diodes and other optoelectronic devices. However, the optical properties of this material greatly depend on the temperature. A clear understanding of temperature dependence exciton dynamics is thus crucial to implement this material in practical applications. Here, we introduce an exhaustive study on the temperature dependence of photoluminescence properties of methyl-ammonium lead iodide (CH 3 NH 3 PbI 3 = MAPbI 3 ) perovskite material from 160K to 270K temperature using Monte Carlo Simulation. We also analyze the phonon-assisted dynamics of localized excitons and their effects on the photoluminescence (PL) spectrum of this material. Our result shows a blue shift behavior of PL peak energy with temperature that is well agreed with experimental results. We also elucidate the Full Width at Half Maximum (FWHM) of CH 3 NH 3 PbI 3 perovskite with same temperature range using Monte Carlo Simulation. These results are very much important to explore the performance of perovskite material based photodevices with wide temperature range.

A new scheme waveguide fabrication for high-speed EAM using local quantum well intermixing (QWI) has been demonstrated. Large blue shift from narrow strip of QWI-induced blue shift forms an optical-index guiding structure, leading to low propagation loss of 0.7dB/100μm in waveguide and >25Gb/s high-speed modulation.

Eu2+ doped Ca 2 Al 2−x Si 1+x O 7−x N x (CASON) green-emitting phosphors were prepared by the high temperature solid state reaction method. The crystal structure and luminescence properties were systematically investigated by X-ray powder diffraction and fluorescence spectrophotometer. It was found that Al-O bond could be substituted by Si-N bond in the Ca 2 Al 2 SiO 7 lattice with the maximum solubility of about x =0.4. Under the excitation of 360nm, the photoluminescence (PL) spectra of Ca 2 Al 2−x Si 1+x O 7−x N x : Eu2+ phosphors presents a blue shift with the increase of x values. The mechanism was discussed in detail by Size-Mismatch model.

We proposed an effective metamaterial infrared (IR) emitter by using MEMS microheater with different pattern density. A highest heating efficiency of MEMS microheater is under the pattern density of 49%. The metamaterial is composed of $\pmb{\pi}$ ·shape nanostructures on the surface of MEMS microheater to form a metamaterial IR emitter. By changing gap width of $\pmb{\pi}$ {###} shape metamaterial, the emissivity of IR emitter is blue shift and enhances its emissivity. The emissivity of metamaterial IR emitter is 0.94 at wavelength of $\mathbf{5} \mu{\mathbf{m}}$ . Such design is able to exhibit a narrowband wavelength in IR wavelength range.

Additional losses occurred when introducing a tapered structure to a square ring semiconductor resonator for unidirectional lasing were investigated from the spectral change of lasing. When the taper was added, the center wavelength of lasing was blue shifted because the total cavity loss was increased. Statistical estimation of the additional loss was attempted.

Anomalously large blueshift of Raman OH band was observed while probing water by picosecond vs nanosecond pulses. Temperature distortion of OH band contour was studied by nano/picosecond Raman techniques. It was observed that OH band centroid shifted linearly with temperature for both nanoand picosecond pulses. We explain picosecond Raman spectra features by non-equilibrium dynamics of hydrogen-bonded structures in water.

Photoluminescence (PL) imaging techniques allow self-consistent characterization of 3D transport and absorption properties. They are here applied on various state-of-the-art perovskite absorbers. A dedicated transport model allows to quantify recombination and diffusion processes with a single experiment. On the contrary to the shallow trap concentration, the slow diffusion and long lifetime of charge carriers are unaffected by chemical composition tuning. In the Cs-containing sample, specific micrometric features appear, where we observe a Cs enrichment, a spectral blue shift and a slower PL decay linked to a lower trap concentration. Local absorption properties are also discussed in term of bandgap nature.

Four-junction solar cells require a sub-cell which absorbs across a 1 eV transition for optimal performance. Due to a lack of available lattice-matched materials with the correct bandgap, current high-efficiency 4J devices use lattice-mismatched sub-cells, complicating the fabrication process. Group IV ternary SiGeSn alloys are a promising material system for achieving a lattice-matched material with a 1 eV direct transition, with functional devices having already been demonstrated. However, further investigation of the fundamental properties of relevant SiGeSn alloys is key to fabricating an efficient 4J device. Results from steady-state photoluminescence and spectroscopic ellipsometry are presented for three different compositions compositions of SiGeSn grown lattice-matched to Ge/GaAs on GaAs substrates. The results show the expected blueshift in the fundamental indirect gap, measured through photoluminescence, and the lowest indirect gap around 1 eV, calculated through analysis of the ellipsometry data. The higher energy transitions also show the expected shifts.

Modulation response of GaAs quantum well laser is analytically investigated at microwave to millimeterwave operative frequency region. Effect of gain compression parameter is taken into account for calculating the response function, and the work is centered around $1.55 \mu \mathrm{m}$ . Confinement factor, mirror reflectivity and scattering effect inside the cavity are varied within practical limit to determine the blueshift of peak of response curve. Width of quantum well changes the wavelength of emitted wavelength, and that changes the modulation feature of the device. Threshold of all the tuning parameters are obtained after which the curve becomes flat, which is the limiting condition. Result will play key role in determining its efficiency as optical transmitter when coupled with optical fiber.

A novel terahertz modulator based on graphene is proposed and designed. The device consists of a silicon ridge covered by a graphene sheet. The transmission properties of the proposed structure demonstrate that the introduction of graphene can improve the switching and filtering performance of modulators, and enhance its field confinement capability. In the case of the number of layers, a blue shift can be observed in the center wavelength with increase of graphene layers. Meanwhile, the relationship between the number of layers and the peak of reflection spectra is an inverse proportion function. In addition, we find that the center wavelength is almost unchanged with respect to the different chemical potential, thus the effective refractive indices of the cross section of light propagation direction can be well preserved. These findings will contribute to the research and development of graphene based THz waveguide modulators.

GaSb/GaAs quantum dots (QDs) exhibit the type-II band alignment where the spatial separation between electron and hole wave functions occurs. The carrier recombination is subsequently low, and seems not to be appropriate for light-emitting applications. In this work, the numerical simulations of electroluminescence (EL) from the GaSb/GaAs QD light-emitting diode (LED) are performed. The LED structure contains a single layer of the GaSb QDs which is inserted in a GaAs matrix, and employed as the active region of the LED. Electrical properties of the LED are presented by current density-voltage characteristics. Under forward-biased condition, simulation results indicate that the radiative recombination rate is high around the GaSb/GaAs interface and becomes gradually lower in the middle of each QD owing to the type-II band alignment. Interestingly, the radiative recombination can be enhanced and extend more into the QDs as the forward-biased voltage increases, enabling the possibility to realize light-emitting devices from type-II nanostructures. These observations can be explained by band diagrams. Furthermore, the blueshift in the EL peak energy with increasing the injected current density is found and almost proportional to the third root of the injected current density, confirming that the EL emissions are derived from the QDs.

The optical properties of graphene have been studied using first-principle density functional theory (DFT) calculations. The dielectric function, refractive index and birefringence in parallel and perpendicular polarization of electric field to the plane of graphene under 0 GPa, 5 GPa and 10 GPa pressures have been studied. The values of these parameters at 5 GPa and 10 GPa have been calculated for the first time. In parallel direction, the threshold energy is blue shifted towards the IR region, whereas in perpendicular direction, it is red shifted towards the UV region. The calculated values are in good agreement with the earlier reported values.

The samples of porous InP were grown up by a method of anode electrochemical etching on a substrate (100) InP n-type. The samples were characterized by scanning electronic microscopy (SEM) and photoluminescence (PL) where a blue shift was observed in PL. To remove surface oxides from the surface of porous InP using the thermal cleaning of the samples in a stream of high purity hydrogen. Chemical composition of surface of porous n-InP after in hydrogen probed treatment the method of Energy dispersive X-ray spectroscopy. Size of walls between pores which makes 3–11nm.

We demonstrate two new schemes for DFB optical frequency drift reduction up to 13-GHz, which address issues of previously described methods. Density increase scheme requires only modification of digital data in the preamble and is therefore well-suited for product implementation.

We have experimentally demonstrated all-optical wavelength conversion of PAM-4 signals based on cross gain modulation in a quantum-dot semiconductor optical amplifier. As a result, we have successfully achieved 5-nm regenerative wavelength conversion of 20-Gbit/s PAM-4 signals at the total required input power 4.8 dBm. Moreover, the improvement of BER with signal regeneration effect by uniforming the power intervals of the PAM-4 signal was successfully achieved.

▪ Presented BlueShift: Self-service for orchestrating automated tasks (via APIs) and human tasks for end-to-end transformation process including, application discovery, analysis, artifact transformation and enablement of cloud value-add services. ▪ Demonstrated transformation process for PlantsByWebSphere application, with Liberty Profile runtime as a target in BlueMix (cloud-foundry based platform). ▪ Discussed challenges arising in transformation from application complexity and non-functional requirements.

The humidity and temperature responses of a microfiber coupler (MFC) coated with silica gel are investigated. Two MFC structures with different waist diameters of 2.5 and 3.5 μm were fabricated by fusing and tapering two single-mode fibers using a microheater brushing technique. The influences of the coating thickness and tapered waist diameter on the sensing performance are analyzed. For the proposed sensor with a waist diameter of 2.5 μm and 8-layers thick coating, the change in the relative humidity (RH) results in an exponential blueshift with a maximum sensitivity of 1.6 nm/% RH in the range from 70 to 86% RH. In response to the temperature change, the sensor's transmission spectrum redshifts in a linear fashion with an average sensitivity of 0.55 nm/°C in the range from 20 to 40 °C. The study is important for the development of the proposed fiber structure as a humidity or temperature sensor.

A new electroabsorption modulator (EAM) has been demonstrated using quantum well intermixing (QWI) method. Through local area of QWI, 110nm wavelength blue shift was attained in strip pattern of SiO2 deposition, forming optical waveguide structure and also leading to sensitive and efficiency voltage-driven optical modulation.

We study the electrostatic discharge (ESD) degradation behavior of 10G uncooled ridge waveguide semiconductor lasers. Using electrical and optical measurements, we show correlation between the ESD degradation and wavelength blue shift. We discuss the physical mechanism of the blue shift.

We investigate the terahertz (THZ) responses of fractal concentric rectangular square resonators (CRS) induced by different mode coupling mechanisms. Near-field coupling results in the resonant mode redshift, while conductive coupling cause the results in the resonant mode blueshift. One can achieve a high Q mode with strong modulation depth by switching the capacitive coupling to conductive coupling in a fractal meta-atom.