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Coupled micro-Doppler signatures of closely located targets
摘要： The classical Doppler shift originates from the movement of a target’s center of mass, but it does not hold information about the internal dynamics of the scattering object. In contrast, micro-Doppler signatures contain data about the micromotions that arise from internal degrees of freedom within the target (such as rotation and vibration), which can be remotely detected by careful analysis of the scattered ?eld. Here we investigate, both theoretically and experimentally, how coupling between a pair of closely situated targets affects the resulting micro-Doppler signatures. The presented model considers a pair of near-?eld coupled resonators with dynamically recon?gurable scattering properties. Voltage controlled varactor diodes enable modulating the scattering cross section of each target independently, mimicking rotational degrees of freedom. As a result, coupled micro-Doppler combs are observed, containing frequency components that arise from the near ?eld interactions, making it possible to extract information about the internal geometry of the system from far-?eld measurements. From a practical point of view, micro-Doppler spectroscopy allows remote classi?cation of distant objects, while deep understanding of the coupling effects on such signatures in the low frequency regime can provide valuable insight for radar and sonar systems, as well as optical and stellar radio-interferometry, among many others.
关键词： sonar,coupled resonators,stellar radio-interferometry,micro-Doppler signatures,radar,optical interferometry
更新于2025-09-16 10:30:52
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Nonlinear operation of resonant sensors based on weakly-coupled resonators: Experimental investigation of an actively-coupled architecture
摘要： This paper is aimed at the validation of a theoretical analysis of the properties of nonlinearly-operated weakly-coupled resonators (WCRs) for resonant sensing applications. In particular, we investigate the relationships between the operating point of such devices and different performance indicators, such as parametric sensitivity, sensitivity to drive level and to noise, and bandwidth. To this end, a couple of high-Q MEMS resonators exhibiting nonlinear restoring and damping forces are used. A careful characterization of the resonators and their associated electronics is made, resulting in a very good, quantitative fit between the experimental results and those predicted by theory.
关键词： Weakly-coupled resonators,Nonlinear oscillations,Resonant sensors
更新于2025-09-16 10:30:52
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A Multipurpose and Highly-Compact Plasmonic Filter based on Metal-Insulator-Metal Waveguides
摘要： A multipurpose and ultra-compact nanoplasmonic wavelength filter based on stub structure in a metal-insulator-metal (MIM) waveguide is suggested and numerically investigated. A novel approach of connecting two stepped-like apertures to both input and output ports is applied to form Fabry-Perot (FP) cavities, which enabled the structure to act as a dual band-pass filter at wavelengths 1310 nm and 1550 nm. It is shown that the variation in cavities’ length allows to realize a long-wavelength cutoff filter, and cutoff wavelength can be easily tuned by adjusting the length of the cavities. Furthermore, it is revealed that increasing the gap between the stepped-like apertures and the cavities provides a triple band-pass at telecom wavelengths, e.g. 1267.5nm, 1414.19 nm, and 1644.7 nm. The tunable broadband high-pass wavelength filter is then achieved while the lengths of stepped-like apertures and stub resonators are set to be identical. Finally, a tunable nearly perfect absorber can be obtained by varying the width of stub resonators. Therefore, because of functionality, size, as well as efficiency the proposed plasmonic filter may greatly contribute to miniaturization of next generation of photonic integrated circuits (PICs), and find applications in on-chip integration and wavelength-division multiplexing (WDM) in optical communication systems.
关键词： wavelength filtering devices,optical filters,Coupled resonators,photonic integrated circuits,surface plasmon polaritons,Fabry-Perot
更新于2025-09-16 10:30:52
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Nonlinear operation of resonant sensors based on weakly-coupled resonators: theory and modeling
摘要： This theoretical work investigates the properties of nonlinearly-operated weakly-coupled resonators (WCRs) for resonant sensing applications. We propose an analysis framework for mutually injection-locked oscillators (MILOs) and to nonlinear mode-localized oscillators restoring and damping simplifying assumptions, three sensor architectures are investigated and compared, highlighting several common features such as: (i) the insensitivity of the amplitude ratio output metric to the A-f effect, (ii) the instability of one oscillation state above a threshold amplitude. These results are illustrated and validated using transient simulations. Their range of validity is then discussed with respect finite bandwidth, finite perturbations, measurement noise and nonlinear dissipation-fluctuation.
关键词： resonant sensing,mutually injection-locked oscillators,weakly-coupled resonators,mode-localized oscillators,nonlinear operation
更新于2025-09-11 14:15:04
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[IEEE 2019 IEEE 2nd Ukraine Conference on Electrical and Computer Engineering (UKRCON) - Lviv, Ukraine (2019.7.2-2019.7.6)] 2019 IEEE 2nd Ukraine Conference on Electrical and Computer Engineering (UKRCON) - Study of Perspective of Gaseous Dielectric Parameters Monitoring with Use of Coupled Biconical Resonators
摘要： The advantages of using coupled biconical resonators for monitoring the parameters of gaseous dielectrics are considered in the paper. In this case, one of the resonators is the reference one. Application of coupled biconical resonators makes it possible to detect deviations of the dielectric constant and loss tangent of the test medium with values of the order of 10-4 and 10-5 correspondingly.
关键词： coupled resonators,Q-factor,biconical resonator,resonance frequency,the complex dielectric constant
更新于2025-09-11 14:15:04
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Parity-Time-Anyonic Coupled Resonators System With Tunable Exceptional Points
摘要： The Hermiticity of physical observable is the fundamental axioms in quantum mechanics. However, it is found that several non-Hermitian Hamiltonian still have real eigenvalues, especially the parity-time symmetric system. The property of parity-time symmetry leads the system to various nontrivial physics with interesting counterintuitive features around the exceptional point. In this study, we investigate the dynamics of parity-time-anyonic Hamiltonian under the tunable exceptional points related to an arbitrary phase of the system. We show that the parity-time symmetry can be achieved in a quasi-parity-time-symmetric system. Also the phase dependence symmetry is discussed based on the simulated results.
关键词： tunable exceptional points,coupled resonators,Parity-time-anyonic
更新于2025-09-11 14:15:04
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[IEEE 2018 IEEE International Conference on Electrical Engineering and Photonics (EExPolytech) - Saint Petersburg, Russia (2018.10.22-2018.10.23)] 2018 IEEE International Conference on Electrical Engineering and Photonics (EExPolytech) - S-Band Microstrip Bandpass Filter Design Based on New Approach to Coupling Coefficients Calculation
摘要： In this paper, a new approach to bandpass filter design, based on coupling coefficients calculation, introduced in [1], is experimentally verified. S-band (2.7 – 3.1 GHz bandwidth) microstrip bandpass filters of several four-resonator structures for pre-selectors of active phase array radar systems are designed, produced and measured. A conventional parallel-coupled filter is produced and measured for comparison. Measurement results confirm good performance of used approach.
关键词： S-band,open-loop resonator,bandpass filter,microstrip,coupled resonators,active phase array radar,pre-selector
更新于2025-09-04 15:30:14
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Quadrature squeezing of the mechanical mode in a superconducting electromechanical system
摘要： We propose a scheme for realizing quadrature squeezing of the mechanical mode in a superconducting electromechanical system, where a nanomechanical resonator (NAMR) is coupled to a superconducting transmission line resonator (STLR) via a superconducting quantum interference device (SQUID), and the SQUID acts as a qubit. Under a large detuning condition, we use the Fr?hlich-Nakajima transformation to adiabatically eliminate the qubit and obtain an effective Hamiltonian for the STLR and the NAMR. Our results show that a strong squeezing effect (beyond 3 dB limit) can occur in the NAMR, and the squeezing degree can be optimized by controlling the strength of the driving field and the dissipation ratio of the system. One of the most notable features of our results is the universality, i.e. the results only depend on a few scaled quantities, not on too many parameters.
关键词： squeezed states,quantum electrodynamics,quantum optics,coupled resonators
更新于2025-09-04 15:30:14