Resonator Configuration Research Articles

Checking the compatibility of the cold Kuiper belt with a planetary instability migration model

The origin of the orbital structure of the cold component of the Kuiper belt is still a hot subject of investigation. Several features of the solar system suggest that the giant planets underwent a phase of global dynamical instability, but the actual dynamical evolution of the planets during the instability is still debated. To explain the structure of the cold Kuiper belt, Nesvorny (2015, AJ 150,68) argued for a ”soft” instability, during which Neptune never achieved a very eccentric orbit. Here we investigate the possibility of a more violent instability, from an initially more compact fully resonant configuration of 5 giant planets. We show that the orbital structure of the cold Kuiper belt can be reproduced quite well provided that the cold population formed in situ, with an outer edge between 44−45 au and never had a large mass.

Analysis and Design of the Ladder Resonant Switched-Capacitor Converters for Regulated Output Voltage Applications

The traditional Ladder switched-capacitor converters have the issues of hard-switching operation and poor line regulation capability. By adding a resonant inductor and substituting a bulky capacitor bank with a small resonant capacitor, its resonant configuration can be obtained and the aforementioned issues could be solved. In addition, by operating the Ladder resonant switched-capacitor converters (RSCs) above the resonance, the optimized operation region is found and some transformational changes can be obtained: the transistors can be operated with zero voltage switching turn-on and diodes are zero current switching turned on/off; the line regulation range is increased significantly for regulated output voltage applications; the instability issue of transition between discontinuous current mode and continuous current mode can be avoided with closed loop; and the voltage/current stress of the resonant tank is reduced. Extensive analysis above and below the resonance is presented to reveal the converter operation modes, voltage-gain curves, output characteristics, and voltage/current stress of the resonant tank. A 3X Ladder RSC prototype for an electronic fuel injection application with maximum output voltage 150 V, maximum power 140 W and peak efficiency 97.6% was designed to be operating in the optimized operation region. The analysis is verified by experimental results.

Stable Green Perovskite Vertical-Cavity Surface-Emitting Lasers on Rigid and Flexible Substrates

Solution processed thin film organo-metal halide perovskites are gaining attention as attractive material prospects for low cost visible and near-infrared lasers while benefiting from recent large investments in photovoltaics of this micro/nanocrystalline material class. A number of reports have demonstrated optically pumped laser action in various optical resonator configurations at comparative low thresholds that might ultimately be compatible with corresponding injection currents required for junction lasers. One major question, however, is the inherent material robustness and stability of the perovskites under what are much higher optical and electronic excitation conditions than encountered in photovoltaics, yet typical in the technologically mature epitaxially grown III–V compound semiconductor lasers. Here we assess CH(NH2)2PbBr3 (FAPbBr3) solid thin films embedded within two sputtered planar dielectric HfO2/SiO2 distributed Bragg reflectors (DBRs) in green perovskite vertical-cavity surface-emitti...

Bi-resonant klynac

Here we present the first analysis of a new device called the bi-resonant klynac, which is a combined klystron and linac. In a bi-resonant klynac, all RF cells, except for the cell that acts as the input for the klystron section, belong to a single resonant circuit. This resonant coupling configuration leads to increased operational stability and can tolerate significant temperature variations. In this paper, a basic analysis of this device is presented, including discussions of how it operates and of the advantages of resonantly coupling the RF generation directly to the linac. We additionally describe the approach used to numerically model the klynac and we include detailed simulations of a 50-kV, 10-A klynac that produces a 1-MeV, 0.1-A output beam. This type of device may be especially useful for situations where an electron beam is needed at low cost.

Ultracompact graphene-assisted ring resonator optical router

Optical routers with compact footprint and low energy consumption are of high demand for optoelectronic integrations. We demonstrate a graphene-assisted optical router based upon silicon ring resonator configurations. The electrical tunability and the influence that graphene has upon the effective mode index are investigated, from monolayer to multiple graphene layers. The corresponding waveguide structure design is further discussed and optimized via numerical simulations. Meanwhile, the design recipes are also discussed and our proposal possesses broad free spectrum range reaching 3.64 THz, lenis crosstalk below −15 dB, low loss and low power consumption that is propitious to versatile wavelength division multiplexing systems and on-chip silicon optical interconnects.

Microfiber Coupling Structures for Magnetic Field Sensing With Enhanced Sensitivity

Two kinds of magnetic field sensors based on Sagnac loop and knot resonator configurations with microfiber coupling structures are proposed and investigated experimentally. The designed sensors are made from the microfiber coupler, whose coupling region is coated with magnetic fluid. The as-fabricated sensors have the same sensing/coupling region, but the achieved sensitivities are greatly different, which are 19.4 and 171.8 pm/Oe for the microfiber Sagnac loop and microfiber knot resonator structures, respectively. Comparing with the microfiber Sagnac loop and other similar microfiber knot resonator (or silicon microring) sensing structures, the sensitivity of the as-designed microfiber knot resonator sensing structure is enhanced significantly. The underlying mechanisms are expounded physically in terms of the microscopic formation of the coupling region and the essence of interference for the microfiber knot resonator structure. The designed structures could potentially lead to highly sensitive magnetic field sensors and other new-fashioned magneto-optical photonic devices.

Optimization Methods for the Design of Sensitive Surface ESR Resonators

Electron spin resonance (ESR) is a powerful spectroscopic technique that has many applications in a wide variety of scientific fields, including chemistry, biology, materials science, and physics. One significant drawback of conventional ESR, however, is its relatively low sensitivity compared to other spectroscopic techniques. Arguably, the most dominant element affecting ESR sensitivity is the microwave resonator used to pick up the ESR signal of the spins. Traditionally, ESR mostly employs a limited set of resonator configurations (e.g., rectangular cavity, dielectric, or loop-gap resonator) that are suboptimal with respect to a wide range of samples. In principle, a smart resonator design can be used to optimize spin sensitivity for a given sample’s properties. In this work, we make use of an efficient Genetic Algorithm (GA) approach to numerically solve, analyze, and optimize a unique class of surface microresonators. The GA is based on a method of moments code, customized directly to render the complexity of a particular resonator’s geometries in our search. The main purposes of the algorithm are to routinely generate more sensitive microresonators, optimized for a predefined sample’s dimensions, and to study the functional relations between the devices’ resonance frequency, quality, and filling factors and their topology, in order to reach a rational optimal design. Preliminary results associated with new, unique, and sensitive surface microresonators are shown and analyzed. Such resonators are cheap and easy to produce on a mass scale with an arbitrary surface geometry.

Improved Planar Resonant RF Sensor for Retrieval of Permittivity and Permeability of Materials

In this paper, the improved planar resonant sensors based on the generalized split ring resonator (SRR) configuration are proposed for the permittivity and the permeability testing of magneto-dielectric samples. It is observed that the proposed inter-digital capacitor-based SRR and the meandered line-based SRR provide better sensitivity for dielectric and magnetic measurement, respectively, when compared with the standard SRR-based microwave sensors. Both the sensors are first modeled under unloaded condition, using the full wave electromagnetic solver, the CST Microwave Studio, in order to ensure their operating frequency range near 2.45 GHz of industrial, scientific and medical band. In the next step, the numerical simulation of these sensors is carried out by loading them with a number of reference materials in order to develop empirical model for the determination of permittivity and permeability of test samples. Additionally, the equivalent circuit models of these sensors are obtained using the Advanced Design System circuit simulator and results are compared with the numerical simulation. All the sensors are designed and fabricated on 1.27-mm-thick RT/Duroid 6006 substrate, and testing is carried out using the network analyzer. A number of standard dielectric and magneto-dielectric samples are tested using the proposed scheme in order to retrieve their permittivity and permeability values. The measured data of each sample are in good match with the corresponding reference values available in literature having a typical error of less than 6%.

Laser testing of anti-reflection micro-structures fabricated in ZnSe and chromium-ion doped ZnSe laser gain media

An expanded study has been completed of the pulsed and continuous wave (CW) laser induced damage threshold (LiDT) of surface relief anti-reflection (AR) microstructures (ARMs) etched in zinc selenide (ZnSe) crystals and chromium-ion-doped (Cr:ZnSe) laser gain media. In multiple-sample per variant testing at wavelengths of 2095 and 2940nm, the pulsed laser damage resistance of ARMs textured ZnSe crystals was found to be equivalent to untreated, as-polished crystals, with an LiDT as much as 5 times that of thin-film AR coated ZnSe crystals. Similar results were found for Cr:ZnSe crystals tested at 2940nm, but mixed results were found for pulse testing at 2095nm. In accumulated power CW damage testing at a wavelength of 1908nm, neither untreated nor ARMs treated ZnSe crystals could be damaged after long duration exposures at a maximum system intensity of 28.6 MW/cm2, a value many times higher than typically found with thin-film AR coated ZnSe. For Cr:ZnSe gain media, the CW LiDT was observed to be dependent on the focused beam size at the sample surface, with thresholds for untreated and ARMs-treated Cr:ZnSe being nearly equivalent, ranging from 0.6 MW/cm2 for the largest spot size, to 2.1 MW/cm2 for a spot area 4 times smaller. An operational laser test was performed where an ARMs textured Cr:ZnSe crystal operated with higher slope efficiency and 1.5 times the output of a thin-film AR coated crystal in an identical resonator configuration.

First trans-Neptunian object in polar resonance with Neptune

Abstract Capture in mean motion resonance has been observed in the Solar system for small objects with prograde as well as retrograde orbits of moderate inclinations. However, no example of an object with a nearly polar orbit was known to be in resonance with a planet. In this Letter, we report that the nearly-polar trans-Neptunian object (471325), nicknamed Niku, is in a 7:9 resonance with Neptune, with a mean lifetime in resonance of 16 ± 11 million years. While entrance and exit in the 7:9 resonance is caused by close encounters with Neptune, the resonant configuration provides a temporary protection mechanism against disruptive close encounters with this planet. The other nearly polar trans-Neptunian objects do not seem to be in resonance with the planets with the possible exception of 2008 KV42, also known as Drac, that has a small chance of being in the 8:13 resonance with Neptune.

An Efficient and Color‐Tunable Solution‐Processed Organic Thin‐Film Laser with a Polymeric Top‐Layer Resonator

Thin film organic lasers represent attractive light sources for numerous applications. Currently, efforts are devoted to the development of low‐cost high‐performance and color‐tunable devices, whereby both the resonator and the active layer should consist of solution‐processable organic materials. Herein, solution‐processed distributed‐feedback lasers are reported with polymeric resonators on top of active films of perylene orange or carbon‐bridged oligo(p‐phenylenevinylene) dispersed in polystyrene, which combine these properties. These lasers emit in the 520–595 nm range and show low thresholds (≈1 kW cm−2) and long operational lifetimes (7 × 105 pump pulses), which are comparable to other state‐of‐the‐art lasers that contain the same active materials but resonators made on inorganic substrates. Due to this top‐layer resonator configuration, the laser slope efficiencies of the present devices are remarkably superior. A centimeter‐size device emitting at different wavelengths within a broad spectral range, based on a perylene‐based film of uniform thickness that contributes to preserve a low threshold, is demonstrated.

High-speed optical three-axis vector magnetometry based on nonlinear Hanle effect in rubidium vapor

The magnetic-field-compensation optical vector magnetometer based on the nonlinear Hanle effect in alkali metal vapor allowing two-axis measurement operation has been further elaborated for three-axis performance, along with significant reduction of measurement time. The upgrade was achieved by implementing a two-beam resonant excitation configuration and a fast maximum searching algorithm. Results of the proof-of-concept experiments, demonstrating 1 μTB-field resolution, are presented. The applied interest and capability of the proposed technique is analyzed.

Misalignment sensitivity in an intra-cavity coherently combined crossed-Porro resonator configuration

We investigate the misalignment sensitivity in a crossed-Porro resonator configuration when coherently combining two pulsed multimode Nd:YAG laser channels. To the best of our knowledge, this is the first reported study of this configuration. The configuration is based on a passive intra-cavity interferometric combiner that promotes self-phase locking and coherent combining. Detailed misalignment sensitivity measurements are presented, examining both translation and angular deviations of the end prisms and combiner, and are compared to the results for standard flat end-mirror configurations. The results show that the most sensitive parameter in the crossed-Porro resonator configuration is the angular tuning of the intra-cavity interferometric combiner, which is ~±54 µrad. In comparison, with the flat end mirror configuration, the most sensitive parameter in the resonator is the angular tuning of the output coupler, which is ~±11 µrad. Thus, with the crossed-Porro configuration, we obtain significantly reduced sensitivity. This ability to reduce the misalignment sensitivity in coherently combined solid-state configurations may be beneficial in paving their way into practical use in a variety of demanding applications.

Design and Characterization of a Meander-Type Dynamic Inductively Coupled Power Transfer Coil

Dynamic inductive coupled power transfer (DICPT) is one of the most promising technologies for railway power supply where no catenary is available and light boarded energy storage system is desired. This paper presents the design and characterization of a DICPT system based on meander-type coils with different geometrical constraints. Constant coupling is demonstrated with a three-phase solution, simplifying dramatically the control stage. A small-scale prototype is built verifying the power transmission equations. Additionally, different resonance configurations are analyzed with the aim of designing the most efficient solution. Finally, electric equations are presented and a 60-kW DICPT system is designed.

Theoretical analysis of microring resonator-based biosensor with high resolution and free of temperature influence

The issue of thermal effects is inevitable for the ultrahigh refractive index (RI) measurement. A biosensor with parallel-coupled dual-microring resonator configuration is proposed to achieve high resolution and free thermal effects measurement. Based on the coupled-resonator-induced transparency effect, the design and principle of the biosensor are introduced in detail, and the performance of the sensor is deduced by simulations. Compared to the biosensor based on a single-ring configuration, the designed biosensor has a 10-fold increased Q value according to the simulation results, thus the sensor is expected to achieve a particularly high resolution. In addition, the output signal of the mathematical model of the proposed sensor can eliminate the thermal influence by adopting an algorithm. This work is expected to have great application potentials in the areas of high-resolution RI measurement, such as biomedical discoveries, virus screening, and drinking water safety.

Over 5-W Passively Q-Switched Mid-Infrared Fiber Laser With a Wide Continuous Wavelength Tuning Range

We report efficient high-average-power, high-energy passively Q-switched operation of an Er3+-doped fluoride fiber laser at room temperature with wavelength-tunable resonator configuration utilizing a plane ruled grating for wavelength selection. The fiber laser produced stable Q-switched pulses with a maximum average output power of 5.16 W at 2811.7 nm and a maximum pulse energy of $27.7~\mu \text{J}$ at 2834.6 nm for 30.5-W launched pump power and could be tuned over a wavelength range of 90 nm from 2762.5 to 2852.5 nm, with > 4-W average power over the range of 76.1 nm. Our results present fivefold increase in output power over previously published values directly attained from ~3- $\mu \text{m}$ passively Q-switched fiber lasers and firmly establish a fiber laser as a compact, wavelength-tunable, multiwatt, tens of microjoules mid-infrared pulse source with large scope of both industrial and scientific applications.

Planetary migration and the origin of the 2:1 and 3:2 (near)-resonant population of close-in exoplanets

We present an analytical and numerical study of the orbital migration and resonance capture of fictitious two-planet systems with masses in the super-Earth range undergoing Type-I migration. We find that, depending on the flare index and proximity to the central star, the average value of the period ratio, $P_2/P_1$, between both planets may show a significant deviation with respect to the nominal value. For planets trapped in the 2:1 commensurability, offsets may reach values on the order of $0.1$ for orbital periods on the order of $1$ day, while systems in the 3:2 mean-motion resonance (MMR) show much smaller offsets for all values of the semimajor axis. These properties are in good agreement with the observed distribution of near-resonant exoplanets, independent of their detection method. We show that 2:1-resonant systems far from the star, such as HD82943 and HR8799, are characterized by very small resonant offsets, while higher values are typical of systems discovered by Kepler with orbital periods approximately a few days. Conversely, planetary systems in the vicinity of the 3:2 MMR show little offset with no significant dependence on the orbital distance. In conclusion, our results indicate that the distribution of Kepler planetary systems around the 2:1 and 3:2 MMR are consistent with resonant configurations obtained as a consequence of a smooth migration in a laminar flared disk, and no external forces are required to induce the observed offset or its dependence with the commensurability or orbital distance from the star.

Convergent Migration Renders TRAPPIST-1 Long-lived

Abstract TRAPPIST-1 is a late M-dwarf orbited by seven Earth-sized planets with orbital period ratios near a chain of mean motion resonances. Due to uncertain system parameters, most orbital configurations drawn from the inferred posterior distribution are unstable on short timescales of ∼0.5 Myr, even when including the eccentricity damping effect of tides. By contrast, we show that most physically plausible resonant configurations generated through disk migration are stable even without tidal dissipation on timescales of at least 50 Myr (1010 orbits), an increase of at least two orders of magnitude. This result, together with the remarkable chain of period ratios in the system, provide strong evidence for convergent migration naturally emplacing the system near an equilibrium configuration forced by the resonant chain. We provide an openly available database of physically plausible initial conditions for TRAPPIST-1 generated through parameterized planet–disk interactions, as well as bit-by-bit reproducible N-body integrations over 109–1010 orbits.

ICRF Traveling Wave launcher for fusion devices

Ion Cyclotron Resonance Heating and Current Drive is a method that has the ability to heat directly the ions in the Deuterium-Tritrium fuel to the high temperature needed for the fusion reaction to works. The capability of efficiently couple the Radio Frequency power to the plasma plays a big role in the overall performance of a fusion device. A Traveling Wave Antenna in a resonant ring configuration is a good candidate for an Ion Cyclotron Resonance Heating and Current Drive system. It has the capability to increase the coupled power with respect to present designs and to have a highly selective power spectrum that can be peaked around the maximally absorbed wave. It is also insensitive to the loading variations due to fluctuation of the plasma edge increasing the reliability and the efficiency of the system. It works as a low power density launcher due to the possible large number of current carrying elements.

Comparison of divertor heat flux splitting by 3D fields with field line tracing simulation in KSTAR

We present the experimental and numerical analysis of divertor heat flux spitting by 3D magnetic fields in KSTAR. A dedicated experiment to measure the modification of the divertor heat flux profile in the n = 2 resonant and non-resonant field configurations has been conducted. The measured heat flux profiles were directly compared to the magnetic field line tracing (FLT) simulation using the POCA-FLT code, which fully considers vacuum and ideal plasma response models. Measurements indicate that the 3D fields induce strong splitting of heat flux on the divertor target due to the formation of stochastic field layers. Splitting characteristics largely depend on the applied 3D field structure and its alignment to the axisymmetric magnetic pitch. The modeling of the field line connection length shows good agreement with measurements, reproducing well the pattern of heat flux splitting. Simulations with the ideal plasma response better reproduce measured heat flux profiles by excitation of non-resonant field components in the non-resonant 0° phase and shielding of resonant field components in the resonant 90° phase.