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This study presents a method for measuring the permittivity of dielectric materials using a whispering gallery mode ring resonator. By detecting changes in coupling resulting from variations in resonant frequency caused by alterations in dielectric constant, the method offers a reliable means of characterizing dielectric properties. Operating within the 5-6 GHz frequency range, the presented resonator design leverages printed circuit board (PCB) technology and FR4 substrate material for cost-effective fabrication and flexibility in design. Through comprehensive electromagnetic simulations using ANSYS HFSS software, the study optimizes resonator parameters to enhance sensitivity and effectiveness for various applications. Experimental validation demonstrates exceptional coupling efficiency and sensitivity, underscoring the potential of whispering gallery mode resonators for environmental monitoring, chemical sensing, telecommunications, and biomedical diagnostics. This research contributes to advancing sensing technology, offering valuable insights into the design and optimization of whispering gallery mode resonators for practical use. Further exploration is warranted to fully realize their potential across diverse applications and operating conditions.

This study presents a method for measuring the permittivity of dielectric materials using a whispering gallery mode ring resonator. By detecting changes in coupling resulting from variations in resonant frequency caused by alterations in dielectric constant, the method offers a reliable means of characterizing dielectric properties. Operating within the 5-6 GHz frequency range, the presented resonator design leverages printed circuit board (PCB) technology and FR4 substrate material for cost-effective fabrication and flexibility in design. Through comprehensive electromagnetic simulations using ANSYS HFSS software, the study optimizes resonator parameters to enhance sensitivity and effectiveness for various applications. Experimental validation demonstrates exceptional coupling efficiency and sensitivity, underscoring the potential of whispering gallery mode resonators for environmental monitoring, chemical sensing, telecommunications, and biomedical diagnostics. This research contributes to advancing sensing technology, offering valuable insights into the design and optimization of whispering gallery mode resonators for practical use. Further exploration is warranted to fully realize their potential across diverse applications and operating conditions.

In many calculation approaches in room acoustics, one models the reflection of surfaces via a positive, real absorption coefficient, neglecting the fact that the reflection coefficient can have a non-zero phase. For some sound-absorbing structures such as resonators, this simplification leads to erroneous results, e.g. when room modes are of interest. This contribution presents an approach for the calculation of room mode frequencies in a rectangular room with complex and frequency-dependent acoustic impedance wall boundary conditions. The results are to be used for auralizations of different scenarios in which the modal behaviour of a room is modified, and for evaluation by listening tests.

The unique mechanical and electrical properties of graphene make it an exciting material for nanoelectromechanical systems (NEMS). NEMS resonators with graphene springs facilitate studies of graphene's fundamental material characteristics and thus enable innovative device concepts for applications such as sensors. Here, we demonstrate resonant transducers with ribbon-springs made of double-layer graphene and proof masses made of silicon and study their nonlinear mechanics at resonance both in air and in vacuum by laser Doppler vibrometry. Surprisingly, we observe spring-stiffening and spring-softening at resonance, depending on the graphene spring designs. The measured quality factors of the resonators in a vacuum are between 150 and 350. These results pave the way for a class of ultraminiaturized nanomechanical sensors such as accelerometers by contributing to the understanding of the dynamics of transducers based on graphene ribbons with an attached proof mass., QC 20240201

As a proof of principle, operation of traveling-wave resonant-tunneling-diodes (RTDs) oscillators has been demonstrated experimentally in the frequency range 100-400 GHz. A theoretical model describing a realistic coupled system, consisting of a traveling-wave RTD and a patch antenna, has been developed. The model describes the eigen resonances and the eigen modes, which have a mixed character of both subsystems. The model and the experimental results are in agreement with each other. We also demonstrate that some oscillators were switching between different resonant modes of the system with the change of bias. The phenomenon could be used for an extended frequency control of the RTD oscillators.

As a proof of principle, operation of traveling-wave resonant-tunneling-diodes (RTDs) oscillators has been demonstrated experimentally in the frequency range 100-400 GHz. A theoretical model describing a realistic coupled system, consisting of a traveling-wave RTD and a patch antenna, has been developed. The model describes the eigen resonances and the eigen modes, which have a mixed character of both subsystems. The model and the experimental results are in agreement with each other. We also demonstrate that some oscillators were switching between different resonant modes of the system with the change of bias. The phenomenon could be used for an extended frequency control of the RTD oscillators.

The aim of this study was to investigate the potential for monitoring chipless RFID technology using a radio transmitter and receiver. The researchers analyzed the behavior of a printed label made with an aluminum-based ink from a thermal printer and compared the read characteristics of the receptor with a baseline. The results showed a shift in the reading characteristics near the resonance point of the curve. In the resonance area, the coded signal deviated from the baseline, floating above the baseline in the slit configuration and below in the line configuration. These observations provide valuable insights into the performance of chipless RFID technology and the potential to optimize its functionality. Chipless RFID technology has the potential to revolutionize the packaging industry by offering a cost-effective and efficient means of tracking and managing inventory. Unlike traditional RFID tags, chipless RFID utilizes the unique characteristics of the packaging material itself to store and transmit data, eliminating the need for expensive chips and simplifying the manufacturing and assembly process. Real-time item tracking, product quality and safety monitoring, and improved supply chain management are among the benefits of chipless RFID, with the potential to enhance efficiency, reduce waste, and increase profitability for companies., El objetivo de este estudio fue investigar el potencial para monitorear la tecnología RFID sin chip usando un transmisor y receptor de radio. Los investigadores analizaron el comportamiento de una etiqueta impresa hecha con una tinta a base de aluminio de una impresora térmica y compararon las características de lectura del receptor con una línea de base. Los resultados mostraron un cambio en las características de lectura cerca del punto de resonancia de la curva. En el área de resonancia, la señal codificada se desvió de la línea de base, flotando por encima de la línea de base en la configuración de rendija y por debajo en la configuración de línea. Estas observaciones brindan información valiosa sobre el rendimiento de la tecnología RFID sin chip y el potencial para optimizar su funcionalidad. La tecnología RFID sin chip tiene el potencial de revolucionar la industria del empaque al ofrecer un medio rentable y eficiente para rastrear y administrar el inventario. A diferencia de las etiquetas RFID tradicionales, la RFID sin chip utiliza las características únicas del propio material de embalaje para almacenar y transmitir datos, eliminando la necesidad de costosos chips y simplificando el proceso de fabricación y ensamblaje. El seguimiento de artículos en tiempo real, la calidad del producto y el control de la seguridad, y la gestión mejorada de la cadena de suministro se encuentran entre los beneficios de RFID sin chip, con el potencial de mejorar la eficiencia, reducir el desperdicio y aumentar la rentabilidad de las empresas.

Lateral modes are responsible for the in-band spurious resonances that appear on BAW resonators, degrading the in-band filter response. In this work, a fast computational method based on the transmission line matrix (TLM) method is employed to model the lateral resonances of BAW resonators. Using the precomputed dispersion curves of Lamb waves and an equivalent characteristic impedance for the TE1 mode, a network of transmission lines is used to calculate the magnitude of field distributions on the electrodes. These characteristics are specific to the stack layer configuration. The model’s implementation is based on nodal Y matrices, from which particle displacement profiles are coupled to the electric domain via piezoelectric constitutive relations. Consequently, the input impedance of the resonator is obtained. The model exhibits strong agreement with FEM simulations of FBARs and SMRs, and with measurements of several SMRs. The proposed model can provide accurate predictions of resonator input impedance, which is around 200 times faster than conventional FEM., This research was funded by the Catalan Government under Grant 2017 SGR 813, by Spanish Government under Grant PID2020-118410RB-C21 and Grant PID2020-113832RB-C21, and by the Secretary of Universities and Research of the Generalitat de Catalunya and the European Social Fund through Grant 2020 FI_B-00967., Peer Reviewed, Postprint (published version)

Producción Científica, Biogas is drawing attention as it can be a solution both to increase the renewable energy for heat or power supply and to help achieve a decarbonized economy. In this work, the measurements of the speed of sound of three mixtures of biogas from the biomethanation plant of the municipal waste of Valdemingómez, Madrid (Spain), are presented. The measurements were performed using an acoustic resonator, which is able to measure the speed of sound of gas mixtures with a relative expanded uncertainty of approximately 0.08%. A virial-type equation was also applied to fit the experimental values of the speed of sound, and the heat capacities as perfect gas were derived with uncertainties below 0.8%. In addition, the experimental results were compared with those calculated with the reference equations of state for natural gas mixtures such as GERG-2008 and AGA8-DC92. For both equations, the average relative deviations were less than 0.02% and 0.2% for the speed of sound and the heat capacities, respectively. These values are less than the uncertainties of these equations, demonstrating their reliability in predicting the thermodynamic behavior of biogas., Junta de Castilla y León y Unión Euopea (UE)-Fondo Europeo de Desarrollo Regional (FEDER) - (grants VA280P18 and CLU-2019-04)

Solidly Mounted Resonators (SMRs) for high frequency RF filters and sensing applications often display spurious resonances that distort their frequency response. In this work, we try to identify the origin of spurious resonances accompanying the main series resonances in AlN-based SMRs with the help of modified Butterworth Van Dyke (BVD) and Mason’s models. By manufacturing SMRs of different sizes and shapes and studying the influence of the position of the electrical probing spot, we have demonstrated both theoretically and experimentally that devices with larger areas are more likely to display these additional peaks. Our updated models accurately simulate the frequency response of the SMRs, revealing that spurious peaks are mostly related to the resistance of the electrodes. Our study clarifies the origin of the spurious resonances and offers solutions for both, the optimal design and measurement method of SMRs., This work was supported in part by the UPC University. Department of Signal and communications [Grant BS123456], CONACYT [grant 291234] Conacyt-Secretaría de Energía-Hidrocarburos 2017 octavo período, R&D National Plan of Spanish Government [PID-2020- 118410RB-C22] and Comunidad de Madrid through the call Research Grants for Young Investigators from Universidad Politécnica de Madrid, ACUEX, APOYO-JOVENES-21-TUGJDU-108-WNZK0H., Peer Reviewed, Postprint (published version)

In the quest for the development of faster and more reliable technologies, the ability to control the propagation, confinement, and emission of light has become crucial. The design of guide mode resonators and perfect absorbers has proven to be of fundamental importance. In this project, we consider the shape optimization of a periodic dielectric slab aiming at efficient directional routing of light to reproduce similar features of a guide mode resonator. For this, the design objective is to maximize the routing efficiency of an incoming wave. That is, the goal is to promote wave propagation along the periodic slab. A Helmholtz problem with a piecewise constant and periodic refractive index medium models the wave propagation, and an accurate Robin-to-Robin map models an exterior domain. We propose an optimal design strategy that consists of representing the dielectric interface by a finite Fourier formula and using its coefficients as the design variables. Moreover, we use a high order finite element (FE) discretization combined with a bilinear Transfinite Interpolation formula. This setting admits explicit differentiation with respect to the design variables, from where an exact discrete adjoint method computes the sensitivities. We show in detail how the sensitivities are obtained in the quasi-periodic discrete setting. The design strategy employs gradient-based numerical optimization, which consists of a BFGS quasi-Newton method with backtracking line search. As a test case example, we present results for the optimization of a so-called single port perfect absorber. We test our strategy for a variety of incoming wave angles and different polarizations. In all cases, we efficiently reach designs featuring high routing efficiencies that satisfy the required criteria.

In the quest for the development of faster and more reliable technologies, the ability to control the propagation, confinement, and emission of light has become crucial. The design of guide mode resonators and perfect absorbers has proven to be of fundamental importance. In this project, we consider the shape optimization of a periodic dielectric slab aiming at efficient directional routing of light to reproduce similar features of a guide mode resonator. For this, the design objective is to maximize the routing efficiency of an incoming wave. That is, the goal is to promote wave propagation along the periodic slab. A Helmholtz problem with a piecewise constant and periodic refractive index medium models the wave propagation, and an accurate Robin-to-Robin map models an exterior domain. We propose an optimal design strategy that consists of representing the dielectric interface by a finite Fourier formula and using its coefficients as the design variables. Moreover, we use a high order finite element (FE) discretization combined with a bilinear Transfinite Interpolation formula. This setting admits explicit differentiation with respect to the design variables, from where an exact discrete adjoint method computes the sensitivities. We show in detail how the sensitivities are obtained in the quasi-periodic discrete setting. The design strategy employs gradient-based numerical optimization, which consists of a BFGS quasi-Newton method with backtracking line search. As a test case example, we present results for the optimization of a so-called single port perfect absorber. We test our strategy for a variety of incoming wave angles and different polarizations. In all cases, we efficiently reach designs featuring high routing efficiencies that satisfy the required criteria.

The correct detection and quantification of pollutants in water is key to regulating their presence in the environment. Biosensors offer several advantages, such as minimal sample preparation, short measurement times, high specificity and sensibility and low detection limits. The purpose of this review is to explore the different types of optical biosensors, focusing on their biological elements and their principle of operation, as well as recent applications in the detection of pollutants in water. According to our literature review, 33% of the publications used fluorescence-based biosensors, followed by surface plasmon resonance (SPR) with 28%. So far, SPR biosensors have achieved the best results in terms of detection limits. Although less common (22%), interferometers and resonators (4%) are also highly promising due to the low detection limits that can be reached using these techniques. In terms of biological recognition elements, 43% of the published works focused on antibodies due to their high affinity and stability, although they could be replaced with molecularly imprinted polymers. This review offers a unique compilation of the most recent work in the specific area of optical biosensing for water monitoring, focusing on both the biological element and the transducer used, as well as the type of target contaminant. Recent technological advances are discussed.

Silicon carbide (SiC) is a suitable candidate for studying hybrid spin-mechanical systems due to its established use as a sensor material[1] and the capability of its hexagonal polytype (4H-SiC) to host highly coherent spin-centers[2], such as silicon vacancies (V_Si). To realize such a system, spin resonances associated with V_Si need to be coupled to the mechanical modes, which will allow more sensitive magnetic field sensing[3]. To achieve this, we will fabricate mechanical resonators in 4H-SiC and create V_Si by helium ion implantation. To study the influence of created V_Si on the mechanical properties, we first considered a system with 3C-SiC (grown on Si) as shown in the figure, which provides higher-quality mechanical resonators compared to 4H-SiC grown on 4H-SiC. In our preliminary experiments, we implanted the resonators with broad beam He+ implantation to create ensembles of V_Si. We intend to show how the mechanical properties can be modified varying fluence, in terms of resonance frequencies, mechanical quality factors and, stress. In future, we plan to use focused He+ implantation to study the positional dependence and number of V_Si on the modification of the material. Finally, we will employ an Optically Detected Spin-Mechanical Resonance (ODSMR) scheme to characterize the coupling of spins and phonons[3]. References: [1] F. Zhao et al., “Photoelectrochemical etching to fabricate single-crystal SiC MEMS for harsh environments”, Materials Letters 65, 409–412 (2011) [2] D. Riedel et al., “Resonant Addressing and Manipulation of Silicon Vacancy Qubits in Silicon Carbide”, Phys.Rev.Lett.109, 226402 (2012) [3] A. V. Poshakinskiy and G. V. Astakhov, "Optically detected spin-mechanical resonance in silicon carbide mem-branes”, PhysRevB.100.094104 (2019)

© 1996 Chapman & Hall Ltd., The influence of super-Gaussian apertures on the beam power, beam size, beam quality factor and kurtosis parameter of Hermite-Gauss mode beams and Gauss Schell-model fields is investigated in detail., Depto. de Óptica, Fac. de Ciencias Físicas, TRUE, pub

Many protocols in quantum science and technology require initializing a system in a pure quantum state. In the context of the motional state of massive resonators, this enables studying fundamental physics at the elusive quantum–classical transition, and measuring force and acceleration with enhanced sensitivity. Laser cooling has been a method of choice to prepare mechanical resonators in the quantum ground state, one of the simplest pure states. However, to overcome the heating and decoherence by the thermal bath, this usually has to be combined with cryogenic cooling. Here, we laser-cool an ultracoherent, soft-clamped mechanical resonator close to the quantum ground state directly from room temperature. To this end, we implement the versatile membrane-in-the-middle setup with one fiber mirror and one phononic crystal mirror, which reaches a quantum cooperativity close to unity already at room temperature. We furthermore introduce a powerful combination of coherent and measurement-based quantum control techniques, which allows us to mitigate thermal intermodulation noise. The lowest occupancy we reach is 30 phonons, limited by measurement imprecision. Doing away with the necessity for cryogenic cooling should further facilitate the spread of optomechanical quantum technologies.

Here, it is proposed an alternative to magnify the sensitivity of a single optical fiber interferometric sensor up to two orders of magnitude. The method consists of fabricating the sensing interferometer with a specific length whose spectrum is added to that of a virtual interferometer whose length is linked to the sensing interferometer. In this manner, the spectrum of the sensing and virtual interferometers are made to coincide in a maximum or a minimum. The pattern resulting from said sum has a well-defined envelope that is easy to monitor and correlate with the measurand. Thus, the sensor sensitivity can be magnified as desirable. To demonstrate the method, a microscopic Fabry-Perot interferometer was fabricated and tested as temperature sensor. A temperature sensitivity amplification of 124 times was demonstrated experimentally. The method here proposed may pave the way to practical implementation of the Vernier effect with a single interferometer or resonator.

Silicon carbide (SiC) is a suitable candidate for studying hybrid spin-mechanical systems due to its established use as a sensor material[1] and the capability of its hexagonal polytype (4H-SiC) to host highly coherent spin-centers[2], such as silicon vacancies (V_Si). To realize such a system, spin resonances associated with V_Si need to be coupled to the mechanical modes, which will allow more sensitive magnetic field sensing[3]. To achieve this, we will fabricate mechanical resonators in 4H-SiC and create V_Si by helium ion implantation. To study the influence of created V_Si on the mechanical properties, we first considered a system with 3C-SiC (grown on Si) as shown in the figure, which provides higher-quality mechanical resonators compared to 4H-SiC grown on 4H-SiC. In our preliminary experiments, we implanted the resonators with broad beam He+ implantation to create ensembles of V_Si. We intend to show how the mechanical properties can be modified varying fluence, in terms of resonance frequencies, mechanical quality factors and, stress. In future, we plan to use focused He+ implantation to study the positional dependence and number of V_Si on the modification of the material. Finally, we will employ an Optically Detected Spin-Mechanical Resonance (ODSMR) scheme to characterize the coupling of spins and phonons[3]. References: [1] F. Zhao et al., “Photoelectrochemical etching to fabricate single-crystal SiC MEMS for harsh environments”, Materials Letters 65, 409–412 (2011) [2] D. Riedel et al., “Resonant Addressing and Manipulation of Silicon Vacancy Qubits in Silicon Carbide”, Phys.Rev.Lett.109, 226402 (2012) [3] A. V. Poshakinskiy and G. V. Astakhov, "Optically detected spin-mechanical resonance in silicon carbide mem-branes”, PhysRevB.100.094104 (2019)

The aim of this study was to investigate the potential for monitoring chipless RFID technology using a radio transmitter and receiver. The researchers analyzed the behavior of a printed label made with an aluminum-based ink from a thermal printer and compared the read characteristics of the receptor with a baseline. The results showed a shift in the reading characteristics near the resonance point of the curve. In the resonance area, the coded signal deviated from the baseline, floating above the baseline in the slit configuration and below in the line configuration. These observations provide valuable insights into the performance of chipless RFID technology and the potential to optimize its functionality. Chipless RFID technology has the potential to revolutionize the packaging industry by offering a cost-effective and efficient means of tracking and managing inventory. Unlike traditional RFID tags, chipless RFID utilizes the unique characteristics of the packaging material itself to store and transmit data, eliminating the need for expensive chips and simplifying the manufacturing and assembly process. Real-time item tracking, product quality and safety monitoring, and improved supply chain management are among the benefits of chipless RFID, with the potential to enhance efficiency, reduce waste, and increase profitability for companies., El objetivo de este estudio fue investigar el potencial para monitorear la tecnología RFID sin chip usando un transmisor y receptor de radio. Los investigadores analizaron el comportamiento de una etiqueta impresa hecha con una tinta a base de aluminio de una impresora térmica y compararon las características de lectura del receptor con una línea de base. Los resultados mostraron un cambio en las características de lectura cerca del punto de resonancia de la curva. En el área de resonancia, la señal codificada se desvió de la línea de base, flotando por encima de la línea de base en la configuración de rendija y por debajo en la configuración de línea. Estas observaciones brindan información valiosa sobre el rendimiento de la tecnología RFID sin chip y el potencial para optimizar su funcionalidad. La tecnología RFID sin chip tiene el potencial de revolucionar la industria del empaque al ofrecer un medio rentable y eficiente para rastrear y administrar el inventario. A diferencia de las etiquetas RFID tradicionales, la RFID sin chip utiliza las características únicas del propio material de embalaje para almacenar y transmitir datos, eliminando la necesidad de costosos chips y simplificando el proceso de fabricación y ensamblaje. El seguimiento de artículos en tiempo real, la calidad del producto y el control de la seguridad, y la gestión mejorada de la cadena de suministro se encuentran entre los beneficios de RFID sin chip, con el potencial de mejorar la eficiencia, reducir el desperdicio y aumentar la rentabilidad de las empresas.

Many protocols in quantum science and technology require initializing a system in a pure quantum state. In the context of the motional state of massive resonators, this enables studying fundamental physics at the elusive quantum–classical transition, and measuring force and acceleration with enhanced sensitivity. Laser cooling has been a method of choice to prepare mechanical resonators in the quantum ground state, one of the simplest pure states. However, to overcome the heating and decoherence by the thermal bath, this usually has to be combined with cryogenic cooling. Here, we laser-cool an ultracoherent, soft-clamped mechanical resonator close to the quantum ground state directly from room temperature. To this end, we implement the versatile membrane-in-the-middle setup with one fiber mirror and one phononic crystal mirror, which reaches a quantum cooperativity close to unity already at room temperature. We furthermore introduce a powerful combination of coherent and measurement-based quantum control techniques, which allows us to mitigate thermal intermodulation noise. The lowest occupancy we reach is 30 phonons, limited by measurement imprecision. Doing away with the necessity for cryogenic cooling should further facilitate the spread of optomechanical quantum technologies.

With the development of communication technology, the allocation of frequency spectrum is becoming more intensive. As an important communication component, reconfigurable filters are widely used in various parts of the communication system. We demonstrate a dual-band reconfigurable (switchable) microstrip bandpass filter working in two sub-6 GHz frequency bands based on controllable grounding topology (CGT), which can achieve an ultra-fast tuning speed up to ~ 2 ns, low bias voltage of ~ 3.0 V and high linearity up to + 42.5 dBm in IP3. We also use the multilayer design to reduce the interference of the bias circuit, and finally, a portable 5G signal detector is proposed, showing the promising application prospects of the proposed switchable bandpass filter. IEEE

The present study proposes a dual-polarized bandwidth-enhanced filtering specialized dipole antenna design for 5G by employing a wide printed dipole, filtering resonators, a reflector surface, and specially designed balun structures. Such a configuration is commonly deployed in conventional base stations. To increase the antenna impedance and radiation bandwidth, a specifically designed, wide-printed flared dipole antenna structure is used as the main radiator element. Transmission zeros are introduced at both pass band edges to create a filtering response by engaging parasitic elements. The parasitic element for the higher frequency edge of the filtering is placed close to the maximum amount of the induced current on the radiator at the operating frequency, whereas the parasitic element for the lower frequency edge of the filtering is located close to the perpendicularly polarized structure. The antenna aims to create radiation nulls at the impedance bandwidth limits; therefore, the parasitic arcs are used to create surface currents that cancel the broadside radiation at the limits of the impedance bandwidth. The study illustrates a complete analysis of the broadband printed patch antenna having a filtering effect by parametric investigations on the dimensions and resulting physical phenomenon in detail. To demonstrate the approach, a prototype of the antenna is fabricated and measured. According to the measurement results, the antenna performs 76% impedance bandwidth between 2.49 GHz and 5.59 GHz with |S11| and |S22| < -10 dB by providing exceptional isolation values of |S21| < -20 dB in entire operating band. The fabricated antenna has a stable radiation beamwidth with less than ± 50 variation and the measured gain in the operating frequency is almost constant and equal to 8.2 dBi., Microelectronics

Many protocols in quantum science and technology require initializing a system in a pure quantum state. In the context of the motional state of massive resonators, this enables studying fundamental physics at the elusive quantum-classical transition, and measuring force and acceleration with enhanced sensitivity. Laser cooling has been a method of choice to prepare mechanical resonators in the quantum ground state, one of the simplest pure states. However, to overcome the heating and decoherence by the thermal bath, this usually has to be combined with cryogenic cooling. Here, we laser-cool an ultracoherent, soft-clamped mechanical resonator close to the quantum ground state directly from room temperature. To this end, we implement the versatile membrane-in-the-middle setup with one fiber mirror and one phononic crystal mirror, which reaches a quantum cooperativity close to unity already at room temperature. We further-more introduce a powerful combination of coherent and measurement-based quantum control techniques, which allows us to mitigate thermal intermodulation noise. The lowest occupancy we reach is 30 phonons, limited by measurement imprecision. Doing away with the necessity for cryogenic cooling should further facilitate the spread of optomechanical quantum technologies. (c) 2023 Optica Publishing Group under the terms of the Optica Open Access Publishing Agreement

The broad application of microelectromechanical systems can be related to the different devices developed for a specific function. Mechanical resonators, filtering applications and temperature sensors are excellent examples of MEMS applications. However, due to the fast-growing demand for MEMS sensors and the harsh environments in which they are subjected (e.g., space exploration, dee-well drilling and fuel combustion), a pursuit for a semiconductor material that can endure these extreme conditions has been carried out. Further, temperature can affect the reliability and accuracy of semiconductor materials due to a narrow band gap (e.g., silicon 1.12 eV, gallium arsenide 1.441 eV and germanium 0.67 eV). Thus, the search for a semiconductor material with a wide energy band gap, high melting point and high electronic operation has generated many candidates (e.g. silicon carbide 2.3-3.2 eV and gallium nitride 3.4 eV, zinc oxide 3.37 eV). Using a wide band gap semiconductor material such as cubic silicon carbide (3C-SiC) allows the fabrication of MEMS devices that endure harsh environments. Additionally, temperature can be used as a positive factor to boost the overall performance of MEMS devices. The research aims to theoretically and experimentally investigate the coupling of thermal effects (e.g., the Joule heating effect, thermal stress and thermoelectric effect) with electro-mechanical properties of SiC (e.g., mechanical stress or strain, piezoresistive effect. SiC/Si heterojunction) to enhance the performance of MEMS devices. The first purpose of this study is to investigate the tunability of a silicon carbide mechanical resonator by coupling thermal stress and the Joule heating effect. The tunability range of the 3C-SiC structure would be evaluated with respect to the thermal energy generated via applied power. Furthermore, this research intends to examine the thermal-piezoresistive pumping in the double-layer structure (n+3C-SiC/n-3C-SiC resonator). The characte, Thesis (PhD Doctorate), Doctor of Philosophy (PhD), School of Eng & Built Env, Science, Environment, Engineering and Technology, Full Text

Many protocols in quantum science and technology require initializing a system in a pure quantum state. In the context of the motional state of massive resonators, this enables studying fundamental physics at the elusive quantum-classical transition, and measuring force and acceleration with enhanced sensitivity. Laser cooling has been a method of choice to prepare mechanical resonators in the quantum ground state, one of the simplest pure states. However, to overcome the heating and decoherence by the thermal bath, this usually has to be combined with cryogenic cooling. Here, we laser-cool an ultracoherent, soft-clamped mechanical resonator close to the quantum ground state directly from room temperature. To this end, we implement the versatile membrane-in-the-middle setup with one fiber mirror and one phononic crystal mirror, which reaches a quantum cooperativity close to unity already at room temperature. We further-more introduce a powerful combination of coherent and measurement-based quantum control techniques, which allows us to mitigate thermal intermodulation noise. The lowest occupancy we reach is 30 phonons, limited by measurement imprecision. Doing away with the necessity for cryogenic cooling should further facilitate the spread of optomechanical quantum technologies. (c) 2023 Optica Publishing Group under the terms of the Optica Open Access Publishing Agreement

In the quest for the development of faster and more reliable technologies, the ability to control the propagation, confinement, and emission of light has become crucial. The design of guide mode resonators and perfect absorbers has proven to be of fundamental importance. In this project, we consider the shape optimization of a periodic dielectric slab aiming at efficient directional routing of light to reproduce similar features of a guide mode resonator. For this, the design objective is to maximize the routing efficiency of an incoming wave. That is, the goal is to promote wave propagation along the periodic slab. A Helmholtz problem with a piecewise constant and periodic refractive index medium models the wave propagation, and an accurate Robin-to-Robin map models an exterior domain. We propose an optimal design strategy that consists of representing the dielectric interface by a finite Fourier formula and using its coefficients as the design variables. Moreover, we use a high order finite element (FE) discretization combined with a bilinear Transfinite Interpolation formula. This setting admits explicit differentiation with respect to the design variables, from where an exact discrete adjoint method computes the sensitivities. We show in detail how the sensitivities are obtained in the quasi-periodic discrete setting. The design strategy employs gradient-based numerical optimization, which consists of a BFGS quasi-Newton method with backtracking line search. As a test case example, we present results for the optimization of a so-called single port perfect absorber. We test our strategy for a variety of incoming wave angles and different polarizations. In all cases, we efficiently reach designs featuring high routing efficiencies that satisfy the required criteria.

In the quest for the development of faster and more reliable technologies, the ability to control the propagation, confinement, and emission of light has become crucial. The design of guide mode resonators and perfect absorbers has proven to be of fundamental importance. In this project, we consider the shape optimization of a periodic dielectric slab aiming at efficient directional routing of light to reproduce similar features of a guide mode resonator. For this, the design objective is to maximize the routing efficiency of an incoming wave. That is, the goal is to promote wave propagation along the periodic slab. A Helmholtz problem with a piecewise constant and periodic refractive index medium models the wave propagation, and an accurate Robin-to-Robin map models an exterior domain. We propose an optimal design strategy that consists of representing the dielectric interface by a finite Fourier formula and using its coefficients as the design variables. Moreover, we use a high order finite element (FE) discretization combined with a bilinear Transfinite Interpolation formula. This setting admits explicit differentiation with respect to the design variables, from where an exact discrete adjoint method computes the sensitivities. We show in detail how the sensitivities are obtained in the quasi-periodic discrete setting. The design strategy employs gradient-based numerical optimization, which consists of a BFGS quasi-Newton method with backtracking line search. As a test case example, we present results for the optimization of a so-called single port perfect absorber. We test our strategy for a variety of incoming wave angles and different polarizations. In all cases, we efficiently reach designs featuring high routing efficiencies that satisfy the required criteria.

In the quest for the development of faster and more reliable technologies, the ability to control the propagation, confinement, and emission of light has become crucial. The design of guide mode resonators and perfect absorbers has proven to be of fundamental importance. In this project, we consider the shape optimization of a periodic dielectric slab aiming at efficient directional routing of light to reproduce similar features of a guide mode resonator. For this, the design objective is to maximize the routing efficiency of an incoming wave. That is, the goal is to promote wave propagation along the periodic slab. A Helmholtz problem with a piecewise constant and periodic refractive index medium models the wave propagation, and an accurate Robin-to-Robin map models an exterior domain. We propose an optimal design strategy that consists of representing the dielectric interface by a finite Fourier formula and using its coefficients as the design variables. Moreover, we use a high order finite element (FE) discretization combined with a bilinear Transfinite Interpolation formula. This setting admits explicit differentiation with respect to the design variables, from where an exact discrete adjoint method computes the sensitivities. We show in detail how the sensitivities are obtained in the quasi-periodic discrete setting. The design strategy employs gradient-based numerical optimization, which consists of a BFGS quasi-Newton method with backtracking line search. As a test case example, we present results for the optimization of a so-called single port perfect absorber. We test our strategy for a variety of incoming wave angles and different polarizations. In all cases, we efficiently reach designs featuring high routing efficiencies that satisfy the required criteria.

This work presents the study of suspended Y-cut Lithium Niobate shear bulk acoustic resonators for wide band filter applications in the frequency range of 3.5-4.5GHz. The resonators consist of a Lithium Niobate film with Aluminum top interdigitated electrodes (IDE) and floating bottom metal plate. Through vertical electric field excitation, shear bulk acoustic waves are generated in each unit cell of the device functioning as a quasi-independent resonator. Measured devices at 3.7GHz having large relative resonance-antiresonance bandwidth of 16.7% (750MHz), with 2 O impedance at resonance are presented. Suppression of higher order lateral harmonics through etching of trenches in the Lithium Niobate and geometric optimization is discussed.2022-0205, This work is supported by Innosuisse - Schweizerische Agentur für Innovationsförderung under the grant ING-33030.1., Peer Reviewed, Postprint (author's final draft)

A combination of direct current (DC) fields and high amplitude radio frequency (RF) fields is necessary to trap ions in a Paul trap. Such high electric RF fields are usually reached with the help of a resonator in close proximity to the ion trap. Ion trap based quantum computers profit from good vacuum conditions and low heating rates that cryogenic environments provide. However, an impedance matching network between the resonator and its RF source is necessary, as an unmatched resonator would require higher input power due to power reflection. The reflected power would not contribute to the RF trapping potential, and the losses in the cable induce additional heat into the system. The electrical properties of the matching network components change during cooling, and a cryogenic setup usually prohibits physical access to integrated components while the experiment is running. This circumstance leads to either several cooling cycles to improve the matching at cryogenic temperatures or the operation of poorly matched resonators. In this work, we demonstrate an RF resonator that is actively matched to the wave impedance of coaxial cables and the signal source. The active part of the matching circuit consists of a varactor diode array. Its capacitance depends on the DC voltage applied from outside the cryostat. We present measurements of the power reflection, the Q-factor, and higher harmonic signals resulting from the nonlinearity of the varactor diodes. The RF resonator is tested in a cryostat at room temperature and cryogenic temperatures, down to 4.3 K. A superior impedance matching for different ion traps can be achieved with this type of resonator.

A combination of direct current (DC) fields and high amplitude radio frequency (RF) fields is necessary to trap ions in a Paul trap. Such high electric RF fields are usually reached with the help of a resonator in close proximity to the ion trap. Ion trap based quantum computers profit from good vacuum conditions and low heating rates that cryogenic environments provide. However, an impedance matching network between the resonator and its RF source is necessary, as an unmatched resonator would require higher input power due to power reflection. The reflected power would not contribute to the RF trapping potential, and the losses in the cable induce additional heat into the system. The electrical properties of the matching network components change during cooling, and a cryogenic setup usually prohibits physical access to integrated components while the experiment is running. This circumstance leads to either several cooling cycles to improve the matching at cryogenic temperatures or the operation of poorly matched resonators. In this work, we demonstrate an RF resonator that is actively matched to the wave impedance of coaxial cables and the signal source. The active part of the matching circuit consists of a varactor diode array. Its capacitance depends on the DC voltage applied from outside the cryostat. We present measurements of the power reflection, the Q-factor, and higher harmonic signals resulting from the nonlinearity of the varactor diodes. The RF resonator is tested in a cryostat at room temperature and cryogenic temperatures, down to 4.3 K. A superior impedance matching for different ion traps can be achieved with this type of resonator.

In this paper, we present an approach to integer factorization using distributed representations formed with Vector Symbolic Architectures. The approach formulates integer factorization in a manner such that it can be solved using neural networks and potentially implemented on parallel neuromorphic hardware. We introduce a method for encoding numbers in distributed vector spaces and explain how the resonator network can solve the integer factorization problem. We evaluate the approach on factorization of semiprimes by measuring the factorization accuracy versus the scale of the problem. We also demonstrate how the proposed approach generalizes beyond the factorization of semiprimes; in principle, it can be used for factorization of any composite number. This work demonstrates how a well-known combinatorial search problem may be formulated and solved within the framework of Vector Symbolic Architectures, and it opens the door to solving similarly difficult problems in other domains., FTS, BAO, CB, and DK were supported by Intel’s THWAI. BAO and DK were supported by AFOSR FA9550-19-1-0241. DK was supported by the MSCA Fellowship (grant 839179). CJK was supported by the DoD through the NDSEG Fellowship. FTS was supported by Intel and NIH R01-EB026955.

[ES] La tecnología Gap Waveguide representa una alternativa interesante como línea de transmisión de bajas pérdidas, eficiente y de alto rendimiento en frecuencias de microondas y bandas milimétricas. Una de las características que diferencia a esta tecnología de otras existentes es la no necesidad de tener contacto eléctrico entre dos piezas metálicas. En este Trabajo de Fin de Grado (TFG) se propone el diseño de un filtro paso banda en banda K (19.7 a 21.2 GHz) mediante la tecnología GW. Dicho filtro se integrará finalmente con otro, diseñado previamente y que trabaja en la banda Ka (30 GHz), en un diplexor. Por lo tanto, el sistema trabajará simultáneamente en recepción y transmisión en las bandas de 20 y 30 GHz, respectivamente. La aplicación directa de este diseño es integrar el diplexor realizado en este TFG en un sistema completo cuyas aplicaciones son las comunicaciones por satélite en movimiento (SATCOM-onthe-move)., [EN] Gap Waveguide technology represents an interesting alternative as a low-loss, efficient and high-performance transmission line in microwave frequencies and millimeter bands. One of the characteristics that differentiates this technology from existing ones is the lack of electrical contact between two metal parts. In this Bachelor¿s Thesis, the design of a band-pass filter in K band (19.7 to 21.2 GHz) using GW technology is proposed. This filter will finally be integrated with another one, previously designed and working in the Ka band (30 GHz), in a diplexer. Therefore, the system will work simultaneously in reception and transmission in the 20 and 30 GHz bands, respectively. The direct application of this design is to integrate the diplexer made in this Bachelor¿s Thesis into a complete system whose applications are satellite communications in motion (SATCOMon-the-move).

An extremely high scanning-rate beam steering antenna based on coupled resonators is proposed in this paper. Coupling resonators in a controlled manner provides a sharp phase variations across a narrow frequency band, which contributes to the extremely high scanning rate. To steer the beam across broadside, alternating +90° and -90° impedance inverters are employed in the topology. Such a coupled-resonator array antenna is modeled and analyzed by coupling matrix technique, which was conventionally used in filter design. To illustrate the proposed technique, two examples with 50 MHz and 100 MHz bandwidths are designed. Experimental validation is also provided for the 50 MHz bandwidth example, which demonstrates that the proposed antenna reaches a high relative scanning rate of 52.8°/%BW with efficiency of 75%. IEEE

[ES] La tecnología Gap Waveguide representa una alternativa interesante como línea de transmisión de bajas pérdidas, eficiente y de alto rendimiento en frecuencias de microondas y bandas milimétricas. Una de las características que diferencia a esta tecnología de otras existentes es la no necesidad de tener contacto eléctrico entre dos piezas metálicas. En este Trabajo de Fin de Grado (TFG) se propone el diseño de un filtro paso banda en banda K (19.7 a 21.2 GHz) mediante la tecnología GW. Dicho filtro se integrará finalmente con otro, diseñado previamente y que trabaja en la banda Ka (30 GHz), en un diplexor. Por lo tanto, el sistema trabajará simultáneamente en recepción y transmisión en las bandas de 20 y 30 GHz, respectivamente. La aplicación directa de este diseño es integrar el diplexor realizado en este TFG en un sistema completo cuyas aplicaciones son las comunicaciones por satélite en movimiento (SATCOM-onthe-move)., [EN] Gap Waveguide technology represents an interesting alternative as a low-loss, efficient and high-performance transmission line in microwave frequencies and millimeter bands. One of the characteristics that differentiates this technology from existing ones is the lack of electrical contact between two metal parts. In this Bachelor¿s Thesis, the design of a band-pass filter in K band (19.7 to 21.2 GHz) using GW technology is proposed. This filter will finally be integrated with another one, previously designed and working in the Ka band (30 GHz), in a diplexer. Therefore, the system will work simultaneously in reception and transmission in the 20 and 30 GHz bands, respectively. The direct application of this design is to integrate the diplexer made in this Bachelor¿s Thesis into a complete system whose applications are satellite communications in motion (SATCOMon-the-move).

[ES] La tecnología Gap Waveguide representa una alternativa interesante como línea de transmisión de bajas pérdidas, eficiente y de alto rendimiento en frecuencias de microondas y bandas milimétricas. Una de las características que diferencia a esta tecnología de otras existentes es la no necesidad de tener contacto eléctrico entre dos piezas metálicas. En este Trabajo de Fin de Grado (TFG) se propone el diseño de un filtro paso banda en banda K (19.7 a 21.2 GHz) mediante la tecnología GW. Dicho filtro se integrará finalmente con otro, diseñado previamente y que trabaja en la banda Ka (30 GHz), en un diplexor. Por lo tanto, el sistema trabajará simultáneamente en recepción y transmisión en las bandas de 20 y 30 GHz, respectivamente. La aplicación directa de este diseño es integrar el diplexor realizado en este TFG en un sistema completo cuyas aplicaciones son las comunicaciones por satélite en movimiento (SATCOM-onthe-move)., [EN] Gap Waveguide technology represents an interesting alternative as a low-loss, efficient and high-performance transmission line in microwave frequencies and millimeter bands. One of the characteristics that differentiates this technology from existing ones is the lack of electrical contact between two metal parts. In this Bachelor¿s Thesis, the design of a band-pass filter in K band (19.7 to 21.2 GHz) using GW technology is proposed. This filter will finally be integrated with another one, previously designed and working in the Ka band (30 GHz), in a diplexer. Therefore, the system will work simultaneously in reception and transmission in the 20 and 30 GHz bands, respectively. The direct application of this design is to integrate the diplexer made in this Bachelor¿s Thesis into a complete system whose applications are satellite communications in motion (SATCOMon-the-move).

Resonators are useful structures due to their simplicity in modeling, design, fabrication and measurement. They can be measured over a wide range of frequencies, power and temperatures, making them convenient for many experiments. Recently, superconducting resonators started being used to investigate microscopic phenomena which require applied magnetic fields of the order of 1T, such as Majorana physics. For this kind of applications it is important that resonators maintain high quality factors in the presence of magnetic fields. A suitable candidate easy to fabricate, resilient to applied fields, and simple capacitive coupling is the lumped element resonator. Such a type of resonator has already been used for some experiments that require magnetic fields, but a systematic study on the resonator’s optimal geometry is yet to be undertaken. The aim of this thesis is to investigate the role of lumped element resonator geometry in its quality factor. That is how to optimize the resonator’s design for enhanced performance of the resonator even in the presence of applied magnetic fields., Applied Sciences

Industrial innovation is mostly driven by miniaturization. As a result of remarkable technological advancements in the fields of equipment, materials and production processes, transistor, the fundamental active component in conventional electronics, has shrunk in size. Semiconductor technology is unique in that all performance metrics are enhanced, while at the same time unit prices are reduced. Moore’s Law, which predicts that the number of components per chip will double every two years, was established in 1965, and the industry has been able to keep up with this prophetic prognosis since. Thermal management, on the other hand, has become a key limiting factor for current electronic circuits and is set to put a stop to Moore’s Law. Given the fact that complementary metal oxide semiconductor (CMOS) scaling is reaching fundamental limits, there are several new alternative processing devices and architectures that have been investigated for both traditional integrated circuit (IC) technologies and novel technologies, including new technologies aimed at contributing to advances in scaling progress and cost reductions in manufacturing operations in the coming decades. These factors will encourage the development of new information processing and memory systems, new technologies for integrating numerous features heterogeneously and new system architectural design layouts, among other things. Energy efficiency is advantageous from a sustainability perspective and for consumer electronics, for which fewer power-hungry components mean longer times between charges and smaller batteries. The creation of novel chip-scale tools that can aid in the transfer of information across optical frequencies and microscale photonics between nanoscale electronic devices is now a possibility. Bridging this technological gap may be achieved by plasmonics. The incorporation of plasmonic, photonic and electrical components on a single chip may lead to a number of innovative breakthroughs. Pho, Branschinnovation drivs främst av miniatyrisering. Som ett resultat av anmärkningsvärda tekniska framsteg inom områdena utrustning, material och produktionsprocesser kunde transistoren, den grundläggande aktiva komponenten i samtida elektronik, krympa i storlek. Halvledarteknik är unik genom att alla prestandamått förbättras, samtidigt som enhetspriserna sänks. Moores Lag, som förutspår att antalet komponenter per chip skulle fördubblas vartannat år, inrättades 1965, och branschen har kunnat hålla jämna steg med den profetiska prognosen sedan dess. Termisk hantering, å andra sidan, har blivit en viktig begränsande faktor för nuvarande elektroniska kretsar, och är inställd på att sätta stopp för Moores Lag. Med tanke på att CMOS-skalningen (Complementary Metal Oxide Semiconductor) når grundläggande gränser finns det flera nya alternativa bearbetningsanordningar och arkitekturer som har undersökts för både traditionell integrerad kretsteknik och ny teknik. Ny teknik som syftar till att bidra till framsteg i skalningen av framsteg och kostnadsminskningar i tillverkningsverksamheten under de kommande årtiondena. Dessa faktorer uppmuntrar utvecklingen av nya informationsbehandlings- och minnessystem, ny teknik för att integrera många funktioner heterogent och nya systemarkitekturdesignlayouter, bland annat. Energieffektivitet är fördelaktigt ur ett hållbarhetsperspektiv och för hemelektronik, där färre krafthungriga elektroniker innebär längre tid mellan laddningar och stimulerar för ett mindre energilagringssystem ombord. Skapandet av nya chip-scale verktyg som kan bidra till överföring av information över optiska frekvenser och mikroskala fotonik mellan elektroniska enheter i nanoskala är nu en möjlighet. Överbrygga denna tekniska klyfta kan uppnås av plasmonics. Införlivandet av plasmoniska, fotoniska och elektriska komponenter på ett enda chip kan leda till ett antal innovativa genombrott. Fotoniska integrerade kretsar (PIC-enheter) möjliggör förverkligande av ultras, Vid tidpunkten för framläggandet av avhandlingen var följande delarbeten opublicerade: delarbete II inskickat, III, IV, V manuskript.At the time of the licentiate defence the following papers were unpublished: paper II submitted, III, IV, V manuscript.

Among other possible designs, metamaterials constructed from ensembles of meta-dipoles emerged as a flexible platform to redirect wave fields. We present an acoustic PT-dipole constructed from two Helmholtz resonators with different losses for such acoustic metamaterials. We explore dipole ensembles in a two dimensional space to either concentrate the field in a predefined area or create a silent area. Numerical simulations agree with experimental results and confirm the sound directivity created by the PT-dipole ensembles., Objectius de Desenvolupament Sostenible::9 - Indústria, Innovació i Infraestructura, Postprint (published version)

The Transmission Line Matrix (TLM) method is used to model and predict lateral spurious resonances in a BAW resonator. The dispersive characteristics of the main propagating mode, which are defined by the stack of materials, are considered with dispersive transmission lines along the in-plane lateral directions of the resonator. The particle displacement profiles obtained with the TLM method are coupled to the electric domain. From these, the input impedance of the resonator is obtained. This allows for fast simulations of the lateral resonances using nodal admittance matrices. © 2022 IEEE., This work was supported in part by the Catalan Government under Grant 2017 SGR 813, in part by the Spanish Government under Grant PID2020- 118410RB-C21 and Grant PID2020-113832RB-C21, and was also supported by the Secretary of Universities and Research of the Generalitat de Catalunya and the European Social Fund through grant 2020 FI_B-00967, Peer Reviewed, Postprint (published version)

Measuring vibrations is essential to ensuring building structural safety and machine stability. Predictive maintenance is a central internet of things (IoT) application within the new industrial revolution, where sustainability and performance increase over time are going to be paramount. To reduce the footprint and cost of vibration sensors while improving their performance, new sensor concepts are needed. Here, double-layer graphene membranes are utilized with a suspended silicon proof demonstrating their operation as resonant vibration sensors that show outstanding performance for a given footprint and proof mass. The unveiled sensing effect is based on resonant transduction and has important implications for experimental studies involving thin nano and micro mechanical resonators that are excited by an external shaker., QC 20230227

High index dielectric nanoresonators have gained prominence in nanophotonics due to lower losses compared to plasmonic systems and their ability to sustain both electric and magnetic resonances. The resonances can be engineered to create new types of optical states, such as bound-states in a continuum (BIC) and anapoles. In this work, we report on the optical properties of vertically stacked AlGaAs nanodisk Mie resonators. The nanodisks are designed to support an anapole state in the visible wavelength region (400-700 nm). The vertically stacked nanodisk resonators are fabricated from AlGaAs/GaAs multilayer samples with a fast and scalable patterning method using charged sphere colloidal lithography. Both measurements and finite difference time domain (FDTD) simulations of two and three stacked resonators show a sharp dip in the reflectance spectra at the anapole wavelength. For the 2 and 3 disk stacks the reflectance dip contrast at the anapole wavelength becomes very pronounced in the specular reflectance and is attributed to increased directional scattering due to an antenna effect. FDTD simulations show there is enhanced field confinement in all the disks at the anapole wavelength and the confined energy within the individual disks in the stack is at least 2-5 times greater compared to an isolated single nanodisk of the same dimension. Furthermore, the field confinement consistently increases with adding more disks in the stack. These vertically stacked AlGaAs nanodisk resonators can be a very exciting platform to engineer light matter interactions for linear and non-linear optical applications. The general principles of the fabrication method can be adapted to other wavelength ranges and can also be adapted for other III-V material combinations as well as for Si/SiO2., QC 20230614

The motivation of this work is to analyze the in-band intermodulation distortion (IMD) occurring in surface acoustic wave (SAW) devices, using a recently developed fast method based on the input–output equivalent sources (IOES). The method calculates the equivalent current sources of a given harmonic (H) or IMD, which when applied at the boundaries of any uniform nonlinear region produce the same nonlinearities as the full distributed circuit. The accuracy of the method is validated with a very simplified SAW resonator with ten digits, which is modeled by a discretized Mason-based circuit. The IOES method provides equal results to the ones obtained through harmonic balance (HB) simulations, performed by means of commercial software, being the first 1000 times faster. Once the accuracy of the method is guaranteed, it is used to analyze the measured in-band IMD3 of several lithium tantalite 42° cut leaky SAW (LSAW) resonators with different pitches and duty factors at the B66 long term evolution (LTE) frequency band. Those resonators are comprised of 100 and 20 electrode pairs for the active region and each of the reflectors, respectively, which implies the analysis of a very large distributed nonlinear problem with thousands of nonlinear local sources. The IOES method takes 35.4 s in simulating 51 frequency points, whereas this simulation is not possible using a commercial HB simulator on a general-purpose computer., This work was supported in part by the Spanish Gov. through grants PID2020-118410RB-C21 and PID2020-113832RB-C21 funded by MCIN/AEI/10.13039/50110001103 and by the Catalan Gov. under grant 2017 SGR-813., Peer Reviewed, Postprint (author's final draft)

The objective of this thesis is to have different resonators all centered at 60GHz but able to detect different materials with different permittivities ranging from 4 to 10. The design of these resonators is based on a Ring Resonator and the size of it will depend on the permittivity that it will have to measure and the material it will be manufactured.

The transverse modes in microchip lasers (MCL) appear different from the classical mode theory, as the resonator consists of a set of plane mirrors (similar to semiconductor edge-emitting lasers and VCSELs). Then the parabolic potential is absent, and the electromagnetic radiation is confined in the transverse space of the resonator by other mechanisms, essentially by gain guiding. Thermal lensing also can play some role in confining the radiation. Laser engineers use several intuitive assumptions about the number of supported modes in the resonator, relating with the Fresnel number of the resonator. However, despite some attempts to calculate the modes in such resonators and investigate combined gain with index guiding, no clear and straightforward methods were provided to calculate the beam radiation profiles. We aim to fill this gap by providing analytical and numerical treatment of MCL modes in two dimensions. We analyze the transverse modes in microchip laser formed due to both gain guiding and thermal lensing. Analytical and numerical results are compared with the results of experimental measurements. Using the cylindrical pumping profile approach, we provide a simple 2D theory of the gain-guided and thermal-lens induced modes in such plane-mirror resonators. We estimate the mode beam quality factor dependency on pumping strength. The model is versatile and applicable to wider range of optical resonators consisting of plane mirrors with longitudinal pumping. Finally, we compare the experimental measurements of beam quality factor with our theoretical model., Postprint (author's final draft)

We demonstrate parametric coupling between two modes of a silicon nitride membrane. We achieve the coupling by applying an oscillating voltage to a sharp metal tip that approaches the membrane surface to within a few 100 nm. When the voltage oscillation frequency is equal to the mode frequency difference, the modes exchange energy periodically and faster than their free energy decay rate. This flexible method can potentially be useful for rapid state control and transfer between modes, and is an important step toward parametric spin sensing experiments with membrane resonators.

Recent advances in integrated nonlinear material platforms and low-loss optical microresonators enabled a broad range of chip-scale optical applications, such as optical frequency combs, quantum photonics, and optical signal processing. The aluminum gallium arsenide-on-insulator (AlGaAsOI) platform exhibiting high nonlinearity, strong light confinement, and negligible two-photon absorption has motivated research in realizing highly efficient nonlinear components. Low loss and dispersion engineering are essential for nonlinear processes in waveguides as the former allows for a long nonlinear interaction distance while the latter ensures good phase matching. Constructing waveguides into microresonators can bring the nonlinear efficiency of the device to an unprecedented level but also requires extra considerations concerning the excess losses induced by waveguide bend and coupler, and the dispersion perturbation induced by intermodal coupling. This paper presents the fabrication process and its critical aspects for high Q AlGaAsOI microresonators. We report the highest Q for high-confinement III-V microring resonators that are fabricated using an electron-beam lithography-based patterning process. We also present an efficient coupler that simplifies the post-processing step for fiber-chip coupling. Moreover, we present generic design methods to suppress the avoided mode crossing (AMX) or dispersion defects in microresonators and demonstrate AMX-free AlGaAsOI microresonators.

Cavity electromechanics relies on parametric coupling between microwave and mechanical modes to manipulate the mechanical quantum state, and provide a coherent interface between different parts of hybrid quantum systems. High coherence of the mechanical mode is of key importance in such applications, in order to protect the quantum states it hosts from thermal decoherence. Here, we introduce an electromechanical system based around a softclamped mechanical resonator with an extremely high Q-factor (>10(9)) held at very low (30 mK) temperatures. This ultracoherent mechanical resonator is capacitively coupled to a microwave mode, strong enough to enable ground-state-cooling of the mechanics ((n) over bar (min) = 0:76 +/- 0:16). This paves the way towards exploiting the extremely long coherence times (t(coh) > 100 ms) offered by such systems for quantum information processing and state conversion.

An extremely high scanning-rate beam steering antenna based on coupled resonators is proposed in this paper. Coupling resonators in a controlled manner provides a sharp phase variations across a narrow frequency band, which contributes to the extremely high scanning rate. To steer the beam across broadside, alternating +90° and -90° impedance inverters are employed in the topology. Such a coupled-resonator array antenna is modeled and analyzed by coupling matrix technique, which was conventionally used in filter design. To illustrate the proposed technique, two examples with 50 MHz and 100 MHz bandwidths are designed. Experimental validation is also provided for the 50 MHz bandwidth example, which demonstrates that the proposed antenna reaches a high relative scanning rate of 52.8°/%BW with efficiency of 75%. IEEE

Suspended piezoelectric thin films are key elements enabling high-frequency filtering in telecommunication devices. To meet the requirements of next-generation electronics, it is essential to reduce device thickness for reaching higher resonance frequencies. Here, the high-quality mechanical and electrical properties of graphene electrodes are combined with the strong piezoelectric performance of the free-standing complex oxide, BaTiO3 (BTO), to create ultrathin piezoelectric resonators. It is demonstrated that the device can be brought into mechanical resonance by piezoelectric actuation. By sweeping the DC bias voltage on the top graphene electrode, the BTO membrane is switched between the two poled ferroelectric states. Remarkably, ferroelectric hysteresis is also observed in the resonance frequency, magnitude and Q-factor of the first membrane mode. In the bulk acoustic mode, the device vibrates at 233 GHz. This work demonstrates the potential of combining van der Waals materials with complex oxides for next-generation electronics, which not only opens up opportunities for increasing filter frequencies, but also enables reconfiguration by poling, via ferroelectric memory effect., QN/Steeneken Lab, ImPhys/Practicum support, QN/van der Zant Lab, QN/Steele Lab, QN/Groeblacher Lab, QN/Caviglia Lab, Dynamics of Micro and Nano Systems, QRD/Wimmer Group