Resonance Modulation Research Articles

An Ultra-Compact Optical Modulator using Indium Tin Oxide Materialand Metal-Dielectric-Metal Waveguide Structure

These days Ultra-compact modulators are seeking so much interest in their research area, because these are the main components of optical transmission systems and also Ultra-compact and ultra- high speed semiconductor electronic modulators are very significant for optoelectronic integrated circuits. The resonant modulators can be of very small size therefor we have proposed a compact Indium Tin Oxide (ITO) based Opto- Electronic Modulator in a Metal-Dielectric-Metal Plasmonic Waveguide Structure and utilizing resonance property in the device. The device has dimension of 0.01 μm3 and shows modulation depth approximately 9 dB near telecommunication wavelength of 1.5 μm. All the calculations had been done using Finite Element Method (FEM). We have also studied the applications of the device as a tunable filter near the telecommunication wavelength. Performance of the suggested device is quite acceptable with comparison to device size and considered valuable for photonic integrated circuit.

Power handling of silicon microring modulators.

Silicon photonic wavelength division multiplexing (WDM) transceivers promise to achieve multi-Tbps data rates for next-generation short-reach optical interconnects. In these systems, microring resonators are important because of their low power consumption and small footprint, two critical factors for large-scale WDM systems. However, their resonant nature and silicon's strong optical nonlinearity give rise to nonlinear effects that can deteriorate the system's performance with optical powers on the order of milliwatts, which can be reached on the transmitter side where a laser is directly coupled into resonant modulators. Here, a theoretical time-domain nonlinear model for the dynamics of optical power in silicon resonant modulators is derived, accounting for two-photon absorption, free-carrier absorption and thermal and dispersion effects. This model is used to study the effects of high input optical powers over modulation quality, and experimental data in good agreement with the model is presented. Two major consequences are identified: the importance of a correct initialization of the resonance wavelength with respect to the laser due to the system's bistability; and the existence of an optimal input optical power beyond which the modulation quality degrades.

Ultrasensitive polarization-dependent terahertz modulation in hybrid perovskites plasmon-induced transparency devices

Active control of metamaterial properties with high tunability of both resonant intensity and frequency is essential for advanced terahertz (THz) applications, ranging from spectroscopy and sensing to communications. Among varied metamaterials, plasmon-induced transparency (PIT) has enabled active control with giant sensitivity by embedding semiconducting materials. However, there is still a stringent challenge to achieve dynamic responses in both intensity and frequency modulation. Here, an anisotropic THz active metamaterial device with an ultrasensitive modulation feature is proposed and experimentally studied. A radiative-radiative-coupled PIT system is established, with a frequency shift of 0.26 THz in its sharp transparent windows by polarization rotation. Enabled by high charge-carrier mobility and longer diffusion lengths, we utilize a straightforwardly spin-coated MAPbI3 film acting as a photoactive medium to endow the device with high sensitivity and ultrafast speed. When the device is pumped by an ultralow laser fluence, the PIT transmission windows at 0.86 and 1.12 THz demonstrate a significant reduction for two polarizations, respectively, with a full recovery time of 561 ps. In addition, we numerically prove the validity that the investigated resonator structure is sensitive to the optically induced conductivity. The hybrid system not only achieves resonant intensity and frequency modulations simultaneously, but also preserves the all-optical-induced switching merits with high sensitivity and speed, which enriches multifunctional subwavelength metamaterial devices at THz frequencies.

Nonlinear Modulation of Plasmonic Resonances in Graphene-Integrated Triangular Dimers at Terahertz Frequencies.

Metamaterials made from artificial subwavelength structures hold great potential in designing functional devices at microwave, terahertz, infrared, and optical frequencies. In this work, we study the active switching effect of the plasmonic resonance modes in triangular dimer (DTD) structure using graphene in the terahertz regime. The sole DTD structure can only support a dipolar bonding dimer plasmonic (BDP) mode, whose field enhancement factor at the gap center can reach 67.4. However, with a metallic junction in the dimer, the BDP mode switches to a charge transfer plasmonic (CTP) mode. When changing the metallic junction to a graphene stripe, an active modulation effect of the CTP mode can be realized by altering the nonlinear conductivity of graphene through strong-field terahertz incidence. The proposed design is quite promising in terahertz sensing, amplitude switching and nonlinear effect enhancement, etc.

Magnetic Field Sensor Based on PT-Symmetry Structure With Magnetic Resonators

We report a novel magnetic field sensor based on a PT-symmetry structure with the modulation of magnetic resonators giving advantages of high sensitivity, large sensing range, and low equipment expenses. The structure has a unique band-edge mode whose wavelength is very sensitive to the external magnetic field. The band-edge mode can be used to detect magnetic fields. The sensitivity range is 240-2.435 × 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4</sup> nm/Oe, which is larger than those obtained using other approaches by an average of two-six orders of magnitude. The sensing range is 1300-4500 (Oe), which is larger than those of other approaches by an average of two orders of magnitude. The proposed magnetic field sensor is very important for applications requiring extremely higher sensitivities over a wide magnetic field range.

All‐Dielectric Active Terahertz Photonics Driven by Bound States in the Continuum

The remarkable emergence of all-dielectric meta-photonics governed by the physics of high-index dielectric materials offers a low-loss platform for efficient manipulation and subwavelength control of electromagnetic waves from microwaves to visible frequencies. Dielectric metasurfaces can focus electromagnetic waves, generate structured beams and vortices, enhance local fields for advanced sensing, and provide novel functionalities for classical and quantum technologies. Recent advances in meta-photonics are associated with the exploration of exotic electromagnetic modes called the bound states in the continuum (BICs), which offer a simple interference mechanism to achieve large quality factors (Q) through excitation of supercavity modes in dielectric nanostructures and resonant metasurfaces. Here, a BIC-driven terahertz metasurface with dynamic control of high-Q silicon supercavities that are reconfigurable at a nanosecond timescale is experimentally demonstrated. It is revealed that such supercavities enable low-power, optically induced terahertz switching and modulation of sharp resonances for potential applications in lasing, mode multiplexing, and biosensing.

High-frequency, resonant acousto-optic modulators fabricated in a MEMS foundry platform.

We report the design and characterization of high-frequency, resonant acousto-optic modulators (AOMs) in a micro-electro-mechanical systems (MEMS) foundry process. The doubly resonant cavity design, with short (L ∼10.5 μm) acoustic and optical cavity lengths, allows us to measure acousto-optic modulation at GHz frequencies with high modulation efficiency. In contrast to traditional AOMs, these devices rely on the perturbation induced by the displacement of cavity boundaries, which can be significantly enhanced in a suspended geometry. This platform can serve as the building block for fast 2D spatial light modulators, low-cost integrated free-space optical links, and optically enhanced low-noise RF receivers.

Resonance tracking in a micromechanical device using phononic frequency combs

Micro and nanomechanical resonators have been extensively researched in recent decades for applications to time and frequency references, as well as highly sensitive sensors. Conventionally, the operation of these resonant sensors is implemented using a feedback oscillator to dynamically track variations in the resonant frequency. However, this approach places limitations on the frequency stability of the output response, particularly owing to near-carrier noise shaping, limiting measurement stabilities at short-to-moderate integration times. Here, in this paper, utilizing the recent experimental demonstration of phononic frequency combs, we demonstrate an alternative resonance tracking approach with the potential to provide significant improvements in near-carrier phase noise and long-term stability. In addition, we also showcase comb dynamics mediated resonant frequency modulation which indirectly points to the possible control of inevitable noise processes including thermomechanical fluctuations. This resonant tracking approach may also have general applicability to a number of other physical oscillators.

Alvus

Wireless charging pads such as Qi are rapidly gaining ground, but their limited power supply range still requires precise placement on a specific point. 2-D wireless power transfer (WPT) sheets consisting of coil arrays are one well-known counterpart to extend this range. However, these approaches require custom-made designs by expert engineers; what we need is a WPT system that can be reconfigured by simply placing ready-made modules on the intended surface (e.g., table, floor, shelf board, etc). In this paper, we present "Alvus", a reconfigurable 2-D WPT system which enables such simple construction of WPT surfaces. Our system is based on multihop WPT that composes "virtual power cords" and consists of three types of ready-made resonator modules: (i) transmitter, which outputs energy, (ii) relays, which pass energy down to the next module, and (iii) receivers, which receive energy and charge the loads. We show that power can be transferred efficiently (over 25%) within a range of 19.6 m2 using a single transmitter. We implemented an end-to-end WPT system and demonstrated that Alvus is capable of intuitive construction/reconfiguration of WPT surfaces, as well as automatically deciding the power routes based on the sensed information (e.g., receiver location, module placement, obstructive objects).

A Modular SiC-Based Step-Up Converter With Soft-Switching-Assisted Networks and Internally Coupled High-Voltage-Gain Modules for Wind Energy System With a Medium-Voltage DC-Grid

In this paper, a fully soft-switched silicon carbide (SiC)-based modular step-up resonant converter with magnetically integrated zero current switching voltage doublers is proposed for medium-voltage (MV) dc conversion in wind energy systems. Conventional step-up resonant dc/dc converters employ either high turns-ratio step-up transformer or step-up resonant circuits to achieve step-up voltage conversion. As a result, they require either complicated expensive transformer structure due to high-voltage electrical isolation requirement or highly voltage-gain sensitive step-up resonant circuits, which are not ideal for designing MV converters for wind energy application. In order to solve the aforementioned drawbacks, the proposed converter configuration utilizes both modular step-up resonant circuits and magnetically integrated voltage doublers to achieve the step-up voltage conversion function. The output voltage of each module of the dc/dc step-up converter is regulated through variable frequency control, whereas asymmetrical pulsewidth modulation (APWM) control is utilized to balance all the resonant currents in all the resonant circuit modules in each converter module. Since APWM control is used, a simple passive auxiliary circuit is included in each converter module to extend soft-switching operation over a wide range of operating conditions. Simulation results on a 1-kV/28-kV, 5-MW converter system with commercial 1.2-kV SiC MOSFET modules and experimental results on a laboratory-scale 300-V/4.8-kV, 5.6-kW proof-of-concept prototype with commercial SiC MOSFET and SiC Schottky diodes are provided to validate the theoretical analysis and to highlight the merits of the proposed work.

English

English

Electro-dynamic analysis of smart nanoclay-reinforced plates with integrated piezoelectric layers

• Static and dynamic behaviors of smart sandwich plates are investigated. • Sandwich plates consist a nanoclay/polymer core and two piezoelectric layers. • A mesh-free method based on MLS shape function and FSDT is developed and implemented. • Two morphologies of intercalated stacks and exfoliated nanoclays are considered. Integrating engineering structures with piezoelectric layers as actuator and/or sensor offers smart sandwich structures with controllable static and dynamic deflections. In this paper, a smart sandwich plate consisting of a light nanoclay-reinforced composite core and two piezoelectric face sheets is considered. The static and dynamic behaviors of the proposed smart plate are obtained using their governing coupled electro-mechanical system of equations. In order to facilitate the governing equations, a mesh-free method based on moving least square (MLS) shape function and first order shear deformation (FSDT) is developed and implemented. Two morphologies of intercalated stack and exfoliated nanoclay dispersions are considered in the distribution of the nanoclay into the polymeric matrix. The effects of morphology and volume fraction of the nanoclay, time-dependent loading, and essential boundary condition on the static and dynamic behavior of the smart piezoelectric-integrated nanocomposite plates are examined. In the dynamic analysis, resonance and amplitude modulation phenomena are studied. It is observed that the use of nanoclay, especially with exfoliated morphology, improves the static and the free vibration responses of the smart sandwich plates. Moreover, the frequency of the applied mechanical load has a significant effect on the electro-dynamic response of the proposed smart sandwich plates.

On-chip interrogator based on Fourier transform spectroscopy.

In this paper, the design and the characterization of a novel interrogator based on integrated Fourier transform (FT) spectroscopy is presented. To the best of our knowledge, this is the first integrated FT spectrometer used for the interrogation of photonic sensors. It consists of a planar spatial heterodyne spectrometer, which is implemented using an array of Mach-Zehnder interferometers (MZIs) with different optical path differences. Each MZI employs a 3×3 multi-mode interferometer, allowing the retrieval of the complex Fourier coefficients. We derive a system of non-linear equations whose solution, which is obtained numerically from Newton's method, gives the modulation of the sensor's resonances as a function of time. By taking one of the sensors as a reference, to which no external excitation is applied and its temperature is kept constant, about 92% of the thermal induced phase drift of the integrated MZIs has been compensated. The minimum modulation amplitude that is obtained experimentally is 400 fm, which is more than two orders of magnitude smaller than the FT spectrometer resolution.

Multi-functional terahertz metamaterial using symmetrical and asymmetrical electric split-ring resonator

Abstract We present the electromagnetic coupling effects in four types of electric split-ring resonators (eSRRs). These four designs of eSRRs are based on SRR tailored with single-, dual-, triple-, and quad-split, respectively. The near-field electromagnetic coupling responses indicate the resonance caused from the inductive-capacitive (LC) resonance between eSRRs. According to the patterns of eSRR are symmetrical or asymmetrical configurations, these eSRRs exhibit polarization-dependence, polarization-independence, resonant frequency shifting, resonant intensity modulation, and resonant switching characteristics, respectively. To increase the flexibility and applicability of eSRRs, two patterned eSRR layers are designed on elastic substrate for the enhancement of the resonant tunability. The designs of eSRRs open an avenue to a new direction for future optical applications, which offer significant promise in flexible electronics applications. This work provides future tunable THz designs based on flexible actuation mechanism to deform the geometrical dimensions between eSRRs microstructures.

Transformation of amplification and attenuation through PT-symmetry structure under modulation of resonators

In order to achieve the transformation of amplification and attenuation with one device, we design a parity-time—symmetry structure through resonator modulation. We use the transfer matrix method to study the optical properties of the designed structure. The structure performs amplification along one incidence direction, and attenuation by absorption along the other incidence direction. The contrast of amplification and attenuation, and the corresponding bandwidth can be modulated through the structure parameters. An optimized structure is obtained with the transformation of large amplification and perfect absorption.

Analysis of the Operation of the Microwave Ion Source in the Electron–Cyclotron Resonance Mode for a Portable Neutron Generator

The authors present the results of numerical simulation of the kinetic processes in deuterium microwave-resonator plasmas with electron–cyclotron resonance at a nonuniform distribution of the magnetic and electric fields. For the actual configuration of the resonator module, the authors show the optimal magnetic field distribution in terms of energy efficiency. The solution of the kinetic scheme of the microwave discharge in deuterium plasmas makes it possible to relate the gas-discharge plasma properties with the parameters of the deuterium-ion source: the residual gas pressure, the gas flow into the microwave resonator, the charged particle flows on the wall and into the ion-optical system, the electrical and magnetic field strength and distribution in the resonator, and the power input into it. The results make it possible to reveal and implement generator operation modes with the highest characteristics ever recorded.

Zero-Order Second Harmonic Generation from AlGaAs-on-Insulator Metasurfaces

All-dielectric metasurfaces consist of two-dimensional arrangements of nanoresonators and are of paramount importance for shaping polarization, phase, and amplitude of both fundamental and harmonic optical waves. To date, their reported nonlinear optical properties have been dominated by local features of the individual nanoresonators. However, collective responses typical of either Mie-resonant metamaterials or photonic crystals can potentially boost the control over such optical properties. In this work we demonstrate the generation of a second harmonic optical wave with zero-order diffraction, from a metasurface made out of AlGaAs-on-AlOx nanocylinders arranged with spatial period comparable to the pump telecom wavelength. Upon normal incidence of the pump beam, the modulation of Mie resonances via Bragg scattering at both fundamental and second harmonic frequencies enables paraxial second harmonic light generation by diffraction into the zero order, with a 50-fold increase in detected power within a s...

Targeted Magnetic Resonance Imaging and Modulation of Hypoxia with Multifunctional Hyaluronic Acid-MnO2 Nanoparticles in Glioma.

Manganese dioxide (MnO2 )-based nanoparticles are a promising tumor microenvironment-responsive nanotheranostic carrier for targeted magnetic resonance imaging (MRI) and for alleviating tumor hypoxia. However, the complexity and potential toxicity of the present common synthesis methods limit their clinical application. Herein, multifunctional hyaluronic acid-MnO2 nanoparticles (HA-MnO2 NPs) are synthesized in a simple way by directly mixing sodium permanganate with HA aqueous solutions, which serve as both a reducing agent and a surface-coating material. The obtained HA-MnO2 NPs show an improved water-dispersibility, fine colloidal stability, low toxicity, and responsiveness to the tumor microenvironment (high H2 O2 and high glutathione, low pH). After intravenous injection, HA-MnO2 NPs exhibit a high imaging sensitivity for detecting rat intracranial glioma with MRI for a prolonged period of up to 3 d. These nanoparticles also effectively alleviate the tumor hypoxia in a rat model of intracranial glioma. The downregulation of VEGF and HIF-1α expression in intracranial glioma validates the sustained attenuation effect of HA-MnO2 NPs on tumor hypoxia. These results show that HA-MnO2 NPs can be used for sensitive, targeted MRI detection of gliomas and simultaneous attenuation of tumor hypoxia.

Approaching the Intrinsic Lifetime and Modulating a Graphene Plasmonic Resonance at a Few Hundred GHz

AbstractGraphene‐based metamaterials exhibit large tunability, low insertion loss, and high field confinement compared with metal‐based structures. Graphene‐based metamaterials may find numerous applications in optical modulators, optoelectronic devices, and chemical sensors in the few‐hundred‐GHz and low‐THz regime, constituting a new frontier as electronics and wireless communication continuously push further to higher frequencies. However, the main challenge is overcoming loss in graphene‐based resonant applications. Here, a low‐loss graphene plasmonic resonant modulator is demonstrated that operates at a few hundred GHz and 1 THz. The modulation depth is in excess of 35% with two layers of graphene. Numerical simulations show good agreement with the experimental results and reveal 100–200 fs lifetimes, which are approaching the intrinsic lifetime of the graphene plasmon due to the suppression of loss from phonon and edge scattering. The above values are the closest to electronic frequencies and represent the longest plasmon lifetime and largest modulation depth in graphene plasmon resonance devices reported so far.

Time-of-flight imaging based on resonant photoelastic modulation.

A time-of-flight imaging system is proposed and its working principle demonstrated. To realize this system, a new device, a free-space optical mixer, is designed and fabricated. A scene is illuminated (flashed) with a megahertz-level amplitude-modulated light source, and the reflected light from the scene is collected by a receiver. The receiver consists of the free-space optical mixer, comprising a photoelastic modulator sandwiched between polarizers, placed in front of a standard complementary metal-oxide-semiconductor (CMOS) image sensor. This free-space optical mixer downconverts the megahertz-level amplitude modulation frequencies into the temporal bandwidth of the image sensor. A full-scale extension of the demonstrated system will be able to measure phases and Doppler shifts for the beat tones and use signal processing techniques to estimate the distance and velocity of each point in the illuminated scene with high accuracy.