Array Of Oscillators Research Articles

Attenuation of seismic waves using resonant metasurfaces: A field study on an array of rubber oscillators

Resonant metasurfaces (RMS) have garnered increasing attention as a type of seismic metamaterial for attenuating seismic waves. To date, most research has been limited to numerical simulations with few experimental studies. Here, we first used Comsol Multiphysics to simulate and identify an RMS structure, which is a periodic array of rubber column oscillators, and then conducted a field experiment on a granular layer. The results indicate that our RMS can effectively attenuate seismic waves in both horizontal and vertical directions across an ultra-wide bandgap. Additionally, the RMS demonstrates greater efficiency in attenuating Love waves compared to Rayleigh waves. This observation is well-accounted for by the resonator model we developed. This work demonstrates that even a simple and cost-effective ground-based RMS is capable of mitigating seismic wave-induced vibrations.

Sensitive and real-time monitoring of microbial growth using a dielectric sensor with a 65-GHz LC-oscillator array and polytetrafluoroethylene membrane

In this study, we report a sensitive real-time microbial growth monitoring technique using a complementary metal-oxide semiconductor (CMOS) dielectric sensor with a polytetrafluoroethylene (PTFE) membrane. The sensor comprised an LC oscillator array operating at 65-GHz, whose resonant frequency was altered according to the dielectric properties of the region approximately 15 μm from the surface. We previously reported the rapid detection of viable Escherichia coli suspended in a liquid medium using the dielectric sensor; however, sensing growing cells was challenging owing to their tendency to float outside the effective sensing area in the suspended medium. To address this, we propose a new method to enhance the sensitivity of the device using a PTFE membrane that retains cells inside the effective area during measurement. Experiments using Escherichia coli suggested that the use of the membrane more than doubled sensitivity, reducing inspection times for practical applications. Furthermore, experiments with Lactococcus lactis, Staphylococcus epidermidis, and Saccharomyces cerevisiae demonstrated that this method can be used to monitor the growth of various microbes. In addition, variations in the output values of each oscillator facilitated the determination of microbial characteristics, such as cell size and growth distribution. This microbial growth monitoring technique is expected to find applications across a wide range of fields, such as food inspection, environmental hygiene monitoring, antibiotic susceptibility testing, new drug discovery, and the exploration of beneficial microbes.

High Sensitivity and High Throughput Magnetic Flow CMOS Cytometers with 2D Oscillator Array and Inter-Sensor Spectrogram Cross-correlation.

In the paper, we present an integrated flow cytometer with a 2D array of magnetic sensors based on dual-frequency oscillators in a 65-nm CMOS process, with the chip packaged with microfluidic controls. The sensor architecture and the presented array signal processing allows uninhibited flow of the sample for high throughput without the need for hydrodynamic focusing to a single sensor. To overcome the challenge of sensitivity and specificity that comes as a trade off with high throughout, we perform two levels of signal processing. First, utilizing the fact that a magnetically tagged cell is expected to excite sequentially an array of sensors in a time-delayed fashion, we perform inter-site cross-correlation of the sensor spectrograms that allows us to suppress the probability of false detection drastically, allowing theoretical sensitivity reaching towards sub-ppM levels that is needed for rare cell or circulating tumor cell detection. In addition, we implement two distinct methods to suppress correlated low frequency drifts of singular sensors-one with an on-chip sensor reference and one that utilizes the frequency dependence of the susceptibility of super-paramagnetic magnetic beads that we deploy as tags. We demonstrate these techniques on a 7×7 sensor array in 65 nm CMOS technology packaged with microfluidics with magnetically tagged dielectric particles and cultu lymphoma cancer cells.

High-power in-phase and anti-phase mode emission from linear arrays of resonant-tunneling-diode oscillators in the 0.4-to-0.8-THz frequency range

Oscillators based on resonant tunneling diodes (RTDs) are able to reach the highest oscillation frequency among all electronic THz emitters. However, the emitted power from RTDs remains limited. Here, we propose linear RTD oscillator arrays capable of supporting coherent emission from both in-phase and anti-phase coupled modes. The oscillation modes can be selected by adjusting the mesa areas of the RTDs. Both the modes exhibit constructive interference at different angles in the far field, enabling high-power emission. Experimental demonstrations of coherent emission from linear arrays containing 11 RTDs are presented. The anti-phase mode oscillates at ∼450 GHz, emitting about 0.7 mW, while the in-phase mode oscillates at around 750 GHz, emitting about 1 mW. Moreover, certain RTD oscillator arrays exhibit dual-band operation: changing the bias voltage allows for controllable switching between the anti-phase and in-phase modes. Upon bias sweeping in both directions, a notable hysteresis feature is observed. Our linear RTD oscillator array represents a significant step forward in the realization of large arrays for applications requiring continuous-wave THz radiation with substantial power.

200 GHz single chip microsystems for dynamic nuclear polarization enhanced NMR spectroscopy

Dynamic nuclear polarization (DNP) is one of the most powerful and versatile hyperpolarization methods to enhance nuclear magnetic resonance (NMR) signals. A major drawback of DNP is the cost and complexity of the required microwave hardware, especially at high magnetic fields and low temperatures. To overcome this drawback and with the focus on the study of nanoliter and subnanoliter samples, this work demonstrates 200 GHz single chip DNP microsystems where the microwave excitation/detection are performed locally on chip without the need of external microwave generators and transmission lines. The single chip integrated microsystems consist of a single or an array of microwave oscillators operating at about 200 GHz for ESR excitation/detection and an RF receiver operating at about 300 MHz for NMR detection. This work demonstrates the possibility of using the single chip approach for the realization of probes for DNP studies at high frequency, high field, and low temperature.

Polychromatic photonic Floquet-Bloch oscillations.

Photonic Floquet-Bloch oscillations (FBOs), a new type of Bloch-like oscillations in photonic Floquet lattices, have recently been observed as a typical discrete self-imaging effect. Here, we theoretically investigate the spectral range of approximate photonic Floquet-Bloch oscillations in arrays of evanescently coupled optical waveguides and show the adjustability of the spectral range. At an appropriate amplitude of the Floquet modulation, we have demonstrated approximate photonic FBOs over a broad spectral range, termed "polychromatic photonic Floquet-Bloch oscillations," which manifest as approximate self-imaging of polychromatic beams. Furthermore, by designing the functional form of the Floquet modulation, we can cascade two polychromatic photonic FBOs and further enhance the performance of polychromatic self-imaging. Our results provide a simple and novel mechanism for achieving polychromatic self-imaging in waveguide arrays and may find applications in polychromatic beam shaping and broadband optical signal processing.

Extreme single-excitation subradiance from two-band Bloch oscillations in atomic arrays

Atomic arrays provide an important quantum optical platform with photon-mediated dipole–dipole interactions that can be engineered to realize key applications in quantum information processing. A major obstacle for such applications is the fast decay of the excited states. By controlling two-band Bloch oscillations of single excitation in an atomic array under an external magnetic field, here we show that exotic subradiance can be realized and maintained with orders of magnitude longer than the spontaneous decay time in atomic arrays with the finite size. The key finding is to show a way for preventing the wavepacket of excited states scattering into the dissipative zone inside the free space light cone, which therefore leads to the excitation staying at a subradiant state for an extremely long decay time. We show that such operation can be achieved by introducing a spatially linear potential from the external magnetic field in the atomic arrays and then manipulating interconnected two-band Bloch oscillations along opposite directions. Our results also point out the possibility of controllable switching between superradiant and subradiant states, which leads to potential applications in quantum storage.

Transient traveling breather response of strongly anharmonic array of self-sustained oscillators: Analytical study.

In the present study, we analyze the transient response of a locally excited chain of strongly anharmonic self-sustained oscillators. This discrete system under consideration models the dynamics of genuinely nonlinear, aeroelastic metamaterial. We particularly focus on the transient evolution of the traveling dissipative breathers, forming in locally excited, finite chains of self-sustained oscillators. The genuinely anharmonic nature of the system under consideration turns the asymptotic analysis of the transient regimes arising in this type of model into a highly challenging task. In the present study, we formulate a special analytical approach which allows for a simple, explicit, and fairly accurate analytical description of the amplitude evolution of the breather core towards the steady state as well as its instantaneous position.

VO2 memristor-based frequency converter with in-situ synthesize and mix for wireless internet-of-things

Wireless internet-of-things (WIoT) with data acquisition sensors are evolving rapidly and the demand for transmission efficiency is growing rapidly. Frequency converter that synthesizes signals at different frequencies and mixes them with sensor datastreams is a key component for efficient wireless transmission. However, existing frequency converters employ separate synthesize and mix circuits with complex digital and analog circuits using complementary metal-oxide semiconductor (CMOS) devices, naturally incurring excessive latency and energy consumption. Here we report a highly uniform and calibratable VO2 memristor oscillator, based on which we build memristor-based frequency converter using 8×\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\ imes$$\\end{document}8 VO2 array that can realize in-situ frequency synthesize and mix with help of compact periphery circuits. We investigate the self-oscillation based on negative differential resistance of VO2 memristors and the programmability with different driving currents and calibration resistances, demonstrating capabilities of such frequency converter for in-situ frequency synthesize and mix for 2 ~ 8 channels with frequencies up to 48 kHz for low frequency transmission link. When transmitting classical sensor data (acoustic, vision and spatial) in an end-to-end WIoT experimental setup, our VO2-based memristive frequency converter presents up to 1.45× ~ 1.94× power enhancement with only 0.02 ~ 0.21 dB performance degradations compared with conventional CMOS-based frequency converter. This work highlights the potential in solving frequency converter’s speed and energy efficiency problems in WIoT using high crystalline quality epitaxially grown VO2 and calibratable VO2-based oscillator array, revealing a promising direction for next-generation WIoT system design.

Dynamics of high-power coupled nonlinear oscillator arrays for electronic beam steering technique: case of the triode based van der Pol oscillator

This paper presents the dynamics of coupled nonlinear oscillator arrays (CNOAs) as phase shifter for electronic beam steering technique. The proposed phase shifter uses oscillators of van der Pol type with a fifth-order nonlinear resistance and is built on the two architectures based injection-locked oscillator array (ILOAs) and coupled oscillator arrays (COAs). The dynamics equations of the phase shifter are proposed in the frequency and time domain. With the help of mathematical tools such as bifurcation diagrams, maximum Lyapunov exponent and Hilbert transform, important cartography of different oscillating states is deduced over large range of system parameters. Different behavior of the CNOAs including chaos, 2D-torus, multistability, locked and unlocked states are depicted. The phase shift between output voltages of each pair of coupled oscillators is presented for both architectures. A detailed analysis of locked states shows that the required phase shift is synthesized by slightly varying the frequency of the injected signal, or simply by detuning the free-running frequencies of the edge oscillators in equal but opposite directions. The proposed circuit of the phased shifter is built using the original van der Pol oscillator based on a vacuum triode. The maximal phase shift reaches 63° and 75° respectively for ILOAs and COAs. With the presence of triode in the circuit, the output voltage of each oscillating element in the array reaches 100V around 60KHz and is boosted by increasing the value of the triode bias potential to more than 420V. This, therefore, increases the total power dissipation of a single oscillator in the array to more than 47dB ( 50.12W ). This circuit is a candidate for high-power electronics beam steering at ultrasonic frequency.

Controlling Information Flow in Arrays of Spin-Torque Oscillators

Controlling Information Flow in Arrays of Spin-Torque Oscillators

Traveling spiral wave chimeras in coupled oscillator systems: emergence, dynamics, and transitions

Systems of coupled nonlinear oscillators often exhibit states of partial synchrony in which some of the oscillators oscillate coherently while the rest remain incoherent. If such a state emerges spontaneously, in other words, if it cannot be associated with any heterogeneity in the system, it is generally referred to as a chimera state. In planar oscillator arrays, these chimera states can take the form of rotating spiral waves surrounding an incoherent core, resembling those observed in oscillatory or excitable media, and may display complex dynamical behavior. To understand this behavior we study stationary and moving chimera states in planar phase oscillator arrays using a combination of direct numerical simulations and numerical continuation of solutions of the corresponding continuum limit, focusing on the existence and properties of traveling spiral wave chimeras as a function of the system parameters. The oscillators are coupled nonlocally and their frequencies are drawn from a Lorentzian distribution. Two cases are discussed in detail, that of a top-hat coupling function and a two-parameter truncated Fourier approximation to this function in Cartesian coordinates. The latter allows semi-analytical progress, including determination of stability properties, leading to a classification of possible behaviors of both static and moving chimera states. The transition from stationary to moving chimeras is shown to be accompanied by the appearance of complex filamentary structures within the incoherent spiral wave core representing secondary coherence regions associated with temporal resonances. As the parameters are varied the number of such filaments may grow, a process reflected in a series of folds in the corresponding bifurcation diagram showing the drift speed s as a function of the phase-lag parameter α.

Seismic metasurface on an orthorhombic elastic half-space.

The article is studying a seismic meta-surface in the case of an oscillatory system arranged on the surface of an orthorhombic elastic half-space. The approach is based on the asymptotic hyperbolic-elliptic formulation for the Rayleigh wave excited by prescribed surface loading. The latter results in hyperbolic equations for surface displacements, with the right-hand sides involving the loading components. The derived model allows a formulation for the meta-surface in the form of a periodic spring-mass system attached to the surface as a hyperbolic equation for the horizontal displacement, with smooth contact stresses emerging from averaging the effect of a regular array of oscillators. The associated dispersion relation is constructed and illustrated numerically for both cases of exponential and oscillatory decay.

Modal analysis for localization of harmonic oscillations in nonlinear pendulum arrays subjected to horizontal excitation

This study aims to clarify the reason for the occurrence of localization of harmonic oscillations when an array of N nonlinear pendulums connected by linear torsion springs is subjected to sinusoidal displacement excitation in the horizontal direction. Modal analysis is used to derive the modal equations of motion, which form an autoparametric system when identical pendulums are connected by identical torsion springs. Van der Pol’s method is applied to the modal equations of motion, and subsequently the expressions for the frequency response curves (FRCs) of the harmonic oscillations are obtained. By using the transformation equation from the modal coordinates to the physical coordinates, the FRCs in the physical coordinates are determined. The FRCs in the modal and physical coordinates for N = 2 and 3 and the backbone curves for N = 2 are shown. The numerical simulation results for N = 10 are also compared in the modal and physical coordinates. When multiple modes appear simultaneously, the summation of these modes provides localization in the physical coordinates. The vector diagram helps to visualize the mechanism of the localization. The effect of array imperfection on the FRCs is also briefly discussed. Furthermore, experimental data confirmed that when localization occurred in a two-pendulum array, the two modes appeared simultaneously.

Recurrence recovery in heterogeneous Fermi-Pasta-Ulam-Tsingou systems.

The computational investigation of Fermi, Pasta, Ulam, and Tsingou (FPUT) of arrays of nonlinearly coupled oscillators has led to a wealth of studies in nonlinear dynamics. Most studies of oscillator arrays have considered homogeneous oscillators, even though there are inherent heterogeneities between individual oscillators in real-world arrays. Well-known FPUT phenomena, such as energy recurrence, can break down in such heterogeneous systems. In this paper, we present an approach-the use of structured heterogeneities-to recover recurrence in FPUT systems in the presence of oscillator heterogeneities. We examine oscillator variabilities in FPUT systems with cubic nonlinearities, and we demonstrate that centrosymmetry in oscillator arrays may be an important source of recurrence.

Scale-free avalanches in arrays of FitzHugh-Nagumo oscillators.

The activity in the brain cortex remarkably shows a simultaneous presence of robust collective oscillations and neuronal avalanches, where intermittent bursts of pseudo-synchronous spiking are interspersed with long periods of quiescence. The mechanisms allowing for such coexistence are still a matter of an intensive debate. Here, we demonstrate that avalanche activity patterns can emerge in a rather simple model of an array of diffusively coupled neural oscillators with multiple timescale local dynamics in the vicinity of a canard transition. The avalanches coexist with the fully synchronous state where the units perform relaxation oscillations. We show that the mechanism behind the avalanches is based on an inhibitory effect of interactions, which may quench the spiking of units due to an interplay with the maximal canard. The avalanche activity bears certain heralds of criticality, including scale-invariant distributions of event sizes. Furthermore, the system shows increased sensitivity to perturbations, manifested as critical slowing down and reduced resilience.

Development of an SIS Mixer-Based Low-Noise Amplifier Amenable to Josephson Oscillator Pumping

We propose a low-noise and low-power-consumption microwave amplifier using superconductor-insulator-superconductor (SIS) mixers as quasi-particle frequency up- and down-converters pumped by a Josephson array oscillator in the millimeter-wave band. A proof-of-concept study of an amplifier with two W-band waveguide mixers using Nb/Al-AlOx/Nb junctions in a cascade connection demonstrated an average gain of 6 dB and a noise temperature of 12 K from nearly DC to 5 GHz. We also designed and fabricated a Josephson array oscillator at 100 GHz, which consisted of 31 overdamped Josephson junctions placed at each half-wavelength in an Nb microstrip line. The estimated output power of the oscillator was 0.2 μW at 100 GHz, which can be increased by increasing the number of the oscillator junctions. These results suggest that the proposed SIS mixer-based amplifier is suitable for on-chip integrated circuits to be implemented in large-scale multipixel SIS receivers and quantum computers.

Stability and steady state analysis of mode lock state of medium coupled microwave oscillators

AbstractCoupled microwave oscillators could be potentially considered a good replacement for the feed network of frequency‐diverse arrays. However, previous studies showed that the stability region for a mutually weak‐coupled oscillator array in the Mode Lock State (MLS) is too small to be practical. Besides, by increasing the coupling strength or reducing the initial natural frequency of the oscillators, the current analytical methods lose their accuracy. The final steady‐state and dynamic of a non‐linear Van‐der‐Pol medium‐coupled oscillator array in the MLS is investigated. By using the Kuramoto Model results in analysing the biological cells, an alternative approach is suggested and investigated in the entrainment region for the mode‐locked microwave oscillator array. This approach is accurate even for medium‐coupled oscillator arrays, where the locking range to the beat frequency ratio is greater than 0.1. The stability of the oscillator in this region is investigated by imposing some perturbations in the form of phase noise on the initial signals. Also, the optimum initial condition to design large arrays is investigated using the analysis results. In the described initial conditions for small beat frequencies, the simulation results show that the stability region is much greater than the large beat frequency region. This capability initiates a new practical approach for implementing Frequency Diverse Arrays.

Electrically Detected Magnetic Resonance on a Chip (EDMRoC) for Analysis of Thin-Film Silicon Photovoltaics

Electrically detected magnetic resonance (EDMR) is a spectroscopic technique that provides information about the physical properties of materials through the detection of variations in conductivity induced by spin-dependent processes. EDMR has been widely applied to investigate thin-film semiconductor materials in which the presence of defects can induce the current limiting processes. Conventional EDMR measurements are performed on samples with a special geometry that allows the use of a typical electron paramagnetic resonance (EPR) resonator. For such measurements, it is of utmost importance that the geometry of the sample under assessment does not influence the results of the experiment. Here, we present a single-board EPR spectrometer using a chip-integrated, voltage-controlled oscillator (VCO) array as a planar microwave source, whose geometry optimally matches that of a standard EDMR sample, and which greatly facilitates electrical interfacing to the device under assessment. The probehead combined an ultrasensitive transimpedance amplifier (TIA) with a twelve-coil array, VCO-based, single-board EPR spectrometer to permit EDMR-on-a-Chip (EDMRoC) investigations. EDMRoC measurements were performed at room temperature on a thin-film hydrogenated amorphous silicon (a-Si:H) pin solar cell under dark and forward bias conditions, and the recombination current driven by the a-Si:H dangling bonds (db) was detected. These experiments serve as a proof of concept for a new generation of small and versatile spectrometers that allow in situ and operando EDMR experiments.

Synchronization of silicon thermal free-carrier oscillators

Recent exploration of collective phenomena in oscillator arrays has highlighted the potential to access a range of physical phenomena, from fundamental quantum many-body dynamics to the solution of practical optimization problems using photonic Ising machines. Spontaneous oscillations often arise in these oscillator arrays as an imbalance between gain and loss. Due to coupling between individual arrays, the spontaneous oscillation is constrained and leads to interesting collective behavior, such as synchronized oscillations in optomechanical oscillator arrays, ferromagnetic-like coupling in delay-coupled optical parametric oscillators, and binary phase states in coupled laser arrays. A key aspect of arrays is not only the coupling between the individuals but also their compliance toward neighbor stimuli. One self-sustaining photonic oscillator that can be readily implemented in a scalable foundry-based technology is based on the interaction of free carriers, temperature, and the optical field of a resonant silicon photonic microcavity. Here, we demonstrate that these silicon thermal free-carrier (FC) oscillators are extremely compliant to external excitation and can be synchronized up to their 16th harmonic using a weak seed. Exploring this unprecedented compliance to external stimuli, we also demonstrate robust synchronization between two thermal FC oscillators.