Resonator Components Research Articles

Triple band single layer microwave absorber based on closed loop resonator structures with high stability under oblique incidence

Triple band single layer microwave absorber based on closed loop resonator structures with high stability under oblique incidence

High-Q Nanophotonics over the Full Visible Spectrum Enabled by Hexagonal Boron Nitride Metasurfaces.

All-dielectric optical metasurfaces with high quality (Q) factors have been hampered by the lack of simultaneously lossless and high-refractive-index materials over the full visible spectrum. In fact, the use of low-refractive-index materials is unavoidable for extending the spectral coverage due to the inverse correlation between the bandgap energy (and therefore the optical losses) and the refractive index (n). However, for Mie resonant photonics, smaller refractive indicesare associated with reduced Q factors and low mode volume confinement. Here, symmetry-broken quasiboundstates in the continuum (qBICs) areleveragedto efficiently suppress radiation losses from the low-index (n≈2) van der Waals material hexagonal boron nitride (hBN), realizing metasurfaces with high-Q resonances over the complete visible spectrum. The rational use of low- and high-refractive-index materials as resonator components is analyzed and the insights are harnessed to experimentally demonstrate sharp qBIC resonances with Q factors above 300, spanning wavelengths between 400and 1000nm from a single hBN flake. Moreover, the enhanced electric near fields are utilized to demonstrate second-harmonic generation with enhancement factors above 102 . Theseresults provide a theoretical and experimental framework for the implementation of low-refractive-index materials as photonic media for metaoptics.

Spherotron Tuning in the Centimeter Range

The effect of the systematic component appearance (deceleration and acceleration) during asynchronous electron interaction with an inhomogeneous electromagnetic field suggests not only the academic interest [1–4] (as a new physical phenomenon), but can also have practical usage in special microwave generators of various ranges. Earlier, the following types of devices were proposed: a coaxial diode generator-diotron [5] and a spherotron based on a two-spherical resonator [6, 7]. Along with some advantages, these devices have a significant disadvantage: the frequency tuning of such generators is difficult due to the fixed resonator oscillation type by the given geometry. This article proposes and analyzes a new type of spherotron, the resonator of which consists of a coaxial line segment loaded on a two-spherical capacitor, in which the interaction between radially converging electron beams and an increasing radial electric field of the resonator run. In the coaxial line (the inductive resonator component) there is an impedance transformer (adjustable waveguide transformer with two dielectric plates) [8] consisting of movable quarter-wave washers. Their movement togather changes the resonator frequency and the mutual moving towards and away from each other is the relation with the load. The coaxial line is connected by the pin to the output waveguide. The proposed spherotron calculation showed the possibility of achieving an efficiency of up 30 % and being tuned in the given band of up 30 % with changing the accelerating voltage V0 = 1.12 V. This generator type is demanded in special (small-sized) communication systems, Doppler radar, electronic warfare with frequency tuning [9], in biochemical research and technology [10], in biological research [11], and in molecular synthesis.

New printed slot antennas with etched SIR components in the ground plane

In this study, two new printed slot antennas have been simulated and fabricated using a single layer of FR4 substrate for modern wireless applications. The first printed slot antenna with etched stair-step topology in the ground plane is proposed to achieve the single-band operation. This topology is based on two components of asymmetrical step-impedance resonator (SIR) and one component of symmetrical SIR. The first designed printed slot antenna satisfies the requirements of WLAN applications at 5.75 GHz. The second printed slot antenna is a developed version of the first one with one inserted component of symmetrical SIR and one asymmetrical SIR component to be operated as a multiband antenna applicable for WiMAX, WLAN, and X-band downlink satellite systems at 3.5, 5.75, and 7.75 GHz, respectively. The proposed antennas have small sizes, and competitive electrical specifications than many reported SIR and non-SIR antennas in the literature.

Tunable and Multiple Plasmon-Induced Transparency in a Metasurface Comprised of Silver S-Shaped Resonator and Rectangular Strip

The plasmon-induced transparency (PIT) in planar metasurface comprising of resonators having one S-shaped structure and a rectangular strip (both made of silver) was investigated. It was found that the S-shaped component of metasurface induces a single bright mode, whereas the rectangular strip manifests two bright modes with strong coupling of incidence electromagnetic waves. When both the metasurface components were placed in the proximity, the PIT-like phenomenon was observed. The effects of rotational angle of the metasurface as well as the angle of incidence on the transmission spectra (of the metasurface) were also investigated. Both the transverse electric (TE) and transverse magnetic (TM) waves were used to explore the PIT effect. It was noticed that the PIT window could be easily tuned by altering the horizontal distance between the resonator components (i.e., the S-shaped structure and rectangular strip). It is expected that the proposed metasurface structure would be prudent in switching, ultrafast sensing and optical applications.

Multistage forming analysis of spoke resonator end-wall

Spoke resonator components are typically formed by sheet metal forming operations such as deep drawing and bending. End wall, Spoke and Shell are the main components of spoke resonators. A sheet metal blank of niobium material is used to form the End wall and Spoke for a spoke resonator. This paper presents an elasto-plastic finite element analysis for single stage and multi stage forming of spoke resonator End wall. Numerical simulations were performed to investigate the effect of forming process parameters on localized thinning, residual stresses and study of failure such as tearing or wrinkling. Forming tools like die, punch and binder were modeled by UGNX 8.0, a modeling software and finite element analysis of forming has been simulated by Altair HYPERFORM software. The results of the analysis were used to assess the various forming process. The analysis showed that the multistage forming leads to better uniformity in thickness of component. This data will help in selection of appropriate forming process.

Systematic analysis of carbon-based microdisk resonators

Abstract Unique mechanical, electrical, and chemical properties of carbon-based nanomaterials make them particularly suited for the modern class of micro-electromechanical resonators. Among several micro/nano-electromechanical system (MEMS/NEMS) resonator components, microdisk profile resonators have recently gained significant attention due to their ultra-high-quality factors and facile system-on-chip integration. Here, we apply an analytical model for the dynamics of graphite microdisk resonators encompassing the effects of electrostatic, van der Waals and Casimir forces. We expound on the electrical and mechanical characteristics of the graphite disk resonator and compare the results to those of a conventional disk resonator made of Silicon. Our studies show that graphite has larger capacitance changes and hence larger electrical sensitivity. The first and second resonant peaks are determined to be around 38 MHz and 104 MHz. The larger amplitude response of graphite disk resonator can lead to a larger signal to noise ratio and a quality factor as high as 1.88 × 106, a four-fold increase compared to silicon. We applied the developed model to investigate the emerging class of 2-dimentional (2D) materials. We have shown that a one-atom thick graphene resonator can exhibit sixteen times larger resonant frequency than that of a graphite resonator. The proposed method can find applications in modeling the electromechanical behavior of a variety of resonating systems based on 3D/2D carbon-based nanomaterials.

Modeling acoustic resonators using higher-order equivalent circuits

Helmholtz resonators are widely used, but classical models for the resonators, such as the lumped-element equivalent circuit, are inaccurate for most geometries. This article presents higher-order equivalent circuits for describing the resonators based on the one-dimensional wave equation. Impedance expressions are also derived. These circuits and expressions are given for various constituent resonator components, which may be combined to model resonators with curved, tapered, and straight necks. Resonance frequency predictions using this theory are demonstrated on two realistic resonators. The higher-order predictions are also applied to the theory of side branch attenuators in a duct and the theory of resonator coupling with a mode of an enclosure.

Two-stage travelling-wave thermoacoustic electricity generator for rural areas of developing countries

Abstract Thermoacoustic heat engines convert thermal power into acoustic power with no-moving parts, while the latter can be converted to electricity using linear alternators. Such thermoacoustic electricity generators can be a means of providing inexpensive electricity to developing countries using the simplest fabrication approaches. This paper shows a detailed study of a prototype waste-heat-driven, two-stage, looped-tube, travelling-wave thermoacoustic electricity generator with a branched linear alternator and tuning stub for acoustic impedance matching purposes. The generator was modelled and designed using DeltaEC. To keep the costs down, the working medium was atmospheric air, many resonator components were made of PVC pipes and fittings, heat exchangers were made of automotive parts, while the linear alternator was a commercially available loudspeaker. The prototype generated 14.2 W of electrical power to a load of 9 Ω. The effects of matching stub length, variable resistive loads and heat inputs were investigated. The simulations and measurement results are presented and discussed in detail.

A Fully Integrated Low-Power 30 GHz Complex Dielectric Sensor in a 0.25-$\mu$m BiCMOS Technology

This paper presents an integrated low-power dielectric sensor in K-band frequencies implemented in a $0.25 \mu \mathrm{m}$ SiGe BiCMOS process, including the sensing front-end and readout circuits. The sensor enables the measurement of both real and imaginary part of permittivity of the material under test (MUT). The MUT is exposed on the resonator component in a sensing oscillator, and the oscillator results in permittivity- and conductivity-dependent change in the output frequency and output power, respectively. The frequency information is translated into dc voltage using a frequency discriminator, and the output power is detected using a power detector. The sensor has been calibrated using iso-propanol, ethanediol, and acetone solutions. Methanol–ethanol mixture solutions, in steps of 25% of concentration change, have been used to demonstrate the functionality of the sensor. The selectivity is showed using methanol–ethanol mixtures with concentration differences of 5% around a mixture ratio of 50:50. The chip is $2.3 \text{mm}^{2}$ in size and consumes 60 mW power. The sensor measures complex permittivity within 3.7% accuracy for the real part and 4.3% for the imaginary part. As a compact and low-power solution, the sensor is a potential candidate for minimal invasive investigations of chemicals and bio-materials at mm-wave frequencies.

Band gaps of piezoelectric/piezomagnetic phononic crystal with magneto-electro-elastic interlayer

Laminate piezoelectric (PE)/piezomagnetic (PM) composites consisting of alternating PE and PM layers can facilitate the conversion of energy between electric and magnetic fields, i.e., they possess the magneto-electric (ME) coupling effects, which recently has attracted much attention due to the huge potential applications in the field of high technology. The PE/PM phononic crystal is an ideal material for manufacturing high-tech precision parts such as resonator components, magnetoelectric sensors, weak magnetic field detectors, electric field tunable filters and magnetic field probes. In the practical applications, the adhesive interfaces of PE/PM phononic crystals are prone to deformation and failure during their use, because of the big difference between PE and PM material. In this paper, the magneto-electro-elastic (MEE) interlayer of magneto-electro-mechanical coupling is introduced into the PE/PM phononic crystal. The thickness of the MEE interlayer, the volume fraction of the piezoelectric material in the MEE interlayer and the type of the piezoelectric materials in the MEE interlayer are changed separately, with the thickness of the unit cell kept at a fixed value. The dispersion relation between the k and the is obtained by using the transfer matrix method and Bloch theorem. The influence of MEE interlayer on the band gap characteristics of PE/PM phononic crystal is studied by the dispersion relation diagram. The results show that as the thickness of the MEE interlayer increases, the central frequency of the band gaps shifts toward a higher frequency and the width of band gap becomes wider. As the volume fraction of the piezoelectric material increases, the center frequency and the width of the first band gap decrease. However, the width of the second band gap increases, and the width of the third band gap remains unchanged. The type of piezoelectric material in the MEE interlayer has an obvious influence on both the width and the central frequency of the band gaps. The effect of MEE interlayer on the central frequency of band gap of PE/PM phononic crystal is more significant in the high frequency region than in the low frequency region. Therefore, the width and central frequency of the band gaps can be adjusted to a certain extent by adding different MEE interlayers into the phononic crystal structure when designed.

Thermo-optical and lasing characteristics of Cr^2+-doped CdSe single crystal as tunable coherent source in the mid-infrared

We report on a comprehensive characterization of Cr2+-doped CdSe single crystal as an efficient active material for tunable laser applications in the mid-infrared spectral region. Optical gain, thermo-optical behavior, power efficiency, scalability and wavelength tunability have been thoroughly investigated. Using an antireflection-coated crystal pumped by a Tm-fiber laser at at 1.94 μm, 1-W CW output power and 50% slope efficiency at 2.65 μm emission wavelength have been obtained in a diffraction-limited output beam. An output peak power of 2.5 W has been achieved without significant beam distortion in a quasi-CW regime. Exploiting an intra-cavity diffraction grating in a Littrow configuration, a maximum tuning range of 900 nm from 2.22 to 3.12 μm, limited by the finite bandwidth of resonator components, has been demonstrated with an uncoated crystal.

Erbium doped ZBLAN fiber laser operating in the visible - feasibility study

This work is focused on developing all-fiber green laser in hybrid geometry, based on combination of Er:ZBLAN active fiber and silica fiber-based passive components of optical resonator and deploying Fiber Bragg Gratings (FBGs) as highly selective mirrors for green spectral range. The scope of work covers fundamental spectroscopic characterization of Er:ZBLAN samples, determination of key spectroscopic parameters, modelling the lasing properties and lasing experiments in different pumping geometries. Full Text: PDF ReferencesW.P. Risk, T.R. Gosnell, A.V. Nurmikko, "Compact blue-green lasers", Cambridge University Press. (2003) CrossRef J.Y. Allain, M. Monerie, and H. Poignant, "Tunable green upconversion erbium fibre laser", Electronics Lett., 28 (1992) 111-113 CrossRef Z . Luo, Q. Ruan, M. Zhong, Y. Cheng, R. Yang, B. Xu, H. Xu, Z. Cai, "Compact self-Q-switched green upconversion Er:ZBLAN all-fiber laser operating at 543.4 nm", Optics Lett. 41 (2016) 2258-2261 CrossRef D. E. McCumber, "Einstein relations connecting broadband emission and absorption spectra", Physical Review 136 (1964) 954-957 CrossRef

Microfiber Knot with Taper Interferometer for temperature and refractive index discrimination

A compact sensing structure using two distinct optical devices, a microfiber knot resonator and an abrupt taper-based Mach–Zehnder interferometer (MZI), is presented. The device was fabricated using only CO2 laser processing. The transmission spectrum presents two different components with different sensitivities to different physical and chemical parameters. The sensor was characterized in temperature and refractive index. For temperature sensing in water, the MZI component presents a sensitivity of −196 ± 2 pm/°C while the microfiber knot resonator (MKR) component shows a sensitivity of 25.1 ± 0.9 pm/°C, for water temperature variations of 12 °C. Sensitivities of 1354 ± 14 nm/RIU and −43 ± 4 nm/RIU were achieved for refractive index sensing for the MZI and the MKR components, respectively, in a refractive index range from 1.32823 to 1.33001. The matrix method was used for the simultaneous measurement of temperature and refractive index.

Electrically Conductive Photopatternable Silver Paste for High-Frequency Ring Resonator and Band-Pass Filter

In conventional thick-film technology, there are often problems associated with poor edges, rough surfaces, and reproducibility due to process limitations, especially for high-frequency applications. These difficulties can be circumvented by using thin-film technology, but process cost and complexity remain major concerns. In this context, photopatternable thick-film technology can offer a viable alternative due to its Newtonian rheology, which can facilitate formation of the required sharp edges. We present herein a unique attempt to formulate a photopatternable silver paste with organic (photosensitive polymer) to inorganic (silver and glass) ratio of 30:70, developed in-house by us for fabrication of thick-film-based ring resonator and band-pass filter components. The ring resonator and band-pass component structures were realized by exposing screen-printed film to ultraviolet light at wavelength of 315 nm to 400 nm for 30 s to crosslink the photosensitive polymer. The pattern was subsequently developed using 1% sodium carbonate aqueous solution. For comparison, conventional silver and silver-palladium thick films were produced using in-house formulations. The surface topology and microstructural features were examined by stereomicroscopy and scanning electron microscopy. The smoothness and edge definition of the film were assessed by profilometry. The resistivity of the samples was observed and remained in the range from 3.4 μΩ cm to 3.6 μΩ cm. The electrical properties were compared by measuring the insertion loss characteristics. The results revealed that the ring resonator fabricated using the photopatternable silver paste exhibited better high-frequency properties compared with components based on conventional silver or silver-palladium paste, especially in terms of the resonant frequency of 10.1 GHz (versus 10 GHz designed) with bandwidth of 80 MHz. Additionally, the band-pass filter fabricated using the photopatternable silver paste displayed better center frequency (f0 = 10.588 GHz) and comparable ripple and attenuation bandwidth performance on par with Cu thin film.

Tailoring the Resonance of Bilayer Graphene Sheets by Interlayer sp3 Bonds

Graphene-based resonators are envisioned to build the ultimate limit of two-dimensional nanoelectromechanical system due to their ultrasensitive detection of mass, force, pressure and charge. However, such application has been greatly impeded by their extremely low quality factor. In the present work, we explore, using the large-scale molecular dynamics simulation, the possibility of tailoring the resonance properties of a bilayer graphene sheet (GS) with interlayer sp3 bonds. For the bilayer GS resonator with interlayer sp3 bonds, we discovered that the sp3 bonds can either degrade or enhance the resonance properties of the resonator depending on their density and location. It is found that the distribution of sp3 bonds only along the edges of either pristine or hydrogenated bilayer GS, leads to a greatly enhanced quality factor. A quality factor of ~1.18×105 is observed for a 3.07×15.31 nm2 bilayer GS resonator with sp3 bonds, which is more than 30 times larger comparing with that of a pristine bilayer GS. The present study demonstrates that the resonance properties of a bilayer GS resonator can be tuned by introducing sp3 bonds. This finding provides a useful guideline for the synthesis of the bilayer GS for its application as a resonator component.

L대역 불요파 저감을 위한, UHF대역 CRLH 대역통과 여파기와 소형 대역저지 여파기의 결합 설계

In this paper, we propose a way to improve the quality of L-band wireless communication from unfriendly influential factors lying in the neighboring RF bands. The UHF-band system has resonator components and they generate harmonics as the spurious in the L-band. Therefore, a metamaterial CRLH bandpass filter is designed for the purpose of system miniaturization and smaller insertion loss, and its spurious phenomenon is observed in the frequency domain. And its harmonics in the L-band are suppressed by a compact bandstop filter whose equivalent circuit is newly developed. The design methodology is validated by the equivalent circuit to be compared with commercial full-wave EM software simulations, where the spurious is dropped by 20dB. Also, the advantage of the proposed design is presented by the comparison where our filter is much smaller than the conventional parallel edge coupled filter by over 50%, with excellent harmonic suppression.

Micrometer‐Scale Photonic Circuit Components Based on Propagation of Exciton Polaritons in Organic Dye Nanofibers

A new approach to create micrometer-scale photonic circuits is developed by using the propagation of exciton polaritons in organic dye nanofibers. A microring resonator component with an I/O bus channel is fabricated by micromanipulation of the nanofibers. The component functions as a wavelength filter with a signal extinction of ∼5 dB for visible light.

Optical Isolation Based on Nonreciprocal Micro-Ring Resonator

We propose a nonreciprocal waveguide with different wavevectors for forward and backward propagations. Utilizing this nonreciprocal waveguide, we further compose a nonreciprocal micro-ring resonator, which possesses different phase shifts for clockwise and anticlockwise circulatings. Using this nonreciprocal resonator, more than 20 dB optical isolation can be achieved. This work demonstrates that on-chip optical isolations can be accomplished with simple nonreciprocal resonator components, which can show promising applications for integrated optoelectronic systems.

Photo-thermo-refractive glass co-doped with Nd 3+ as a new laser medium

Abstract Photo-thermo-refractive (PTR) glass demonstrates refractive index change after exposure to UV radiation followed by a thermal treatment that enables recording of high efficiency holographic optical elements. This work demonstrates feasibility of function of this material as a complex optical medium which posseses both photosensitive and luminescent properties and paves a way for creation of monolythic solid state lasers where resonator components can be holographically recorded inside of a laser medium. It was found, that incorporating of Nd3+ ions in PTR glass does not affect photosensitivity required for hologram recording. It was demonstrated that emission wavelength, spectral width, and cross section of Nd3+ luminescence in PTR glass are typical for silicate laser glasses and Nd-doped PTR glass can be considered as a promising laser medium for monolithic solid state lasers.