Resonator Configuration Research Articles

Low Threshold Microlasers Based on Organic-Conjugated Polymers.

Conjugated polymers have emerged as ideal organic laser materials for the excellent optoelectrical properties and facile processability. During a typical lasing process, resonator configurations with specific geometry are essential to provide optical feedback and then amplified light. Herein, we summarized the geometry and working mechanism of several typical resonator configurations formed with conjugated polymers. Meanwhile, recent advances in fabrication techniques and lasing performance are also discussed to provide new ideas for the design and optimization of microcavity geometries. Followed by the advances of practical applications in fields of laser sensing, bioimaging, and laser illumination/display, we make a summary of the existing bottlenecks and future perspectives of electrically driven organic lasers toward laser display and illumination.

Giant Second Harmonic Generation Enhancement in a High-Q Doubly Resonant Hybrid Plasmon-Fiber Cavity System.

A high-quality plasmon-fiber cavity in a doubly resonant configuration can exhibit second-harmonic generation (SHG) with over 5 orders of magnitude enhancement compared to gold nanoparticles on a fused silica substrate. Through coupling to a fiber cavity with the proper diameter, a high-quality (Q ≈ 160) resonance can be achieved in combination with a single gold nanoparticle. In a classical picture, where the incident electric field travels coherently Q times around the fiber during the nonlinear process, the high Q of the coupled mode aids in highly efficient SHG. We accomplish two feats: First, we analyze the Q factor dependence of the SHG efficiency, proving the expected Q4 dependence and thus confirming coherent E-field amplification in the fiber cavity. Second, we carefully adjust the fiber size further and tune the plasmon response of a gold nanoparticle to a high-Q cavity mode. We make sure that the second harmonic wavelength is simultaneously in resonance with a higher order fiber cavity mode, fulfilling the doubly resonant condition. As a result, a giant SH response with conversion efficiency up to 1.6 × 10-5 is detected upon a pump intensity of 5 × 108 W/cm2 for 100 fs pump pulses around 840 nm incident wavelength. Additionally, the importance of the doubly resonant condition is proven by detuning the size of the fiber, which leads to a drastic drop in SHG efficiency. This disparity of the SHG efficiency can be observed even by eye, when monitoring the intensity changes of the visible SH light during detuning.

A new expansion of planetary disturbing function and applications to interior, co-orbital and exterior resonances with planets

In this study, a new expansion of planetary disturbing function is developed for describing the resonant dynamics of minor bodies with arbitrary inclinations and semimajor axis ratios. In practice, the disturbing function is expanded around circular orbits in the first step and then, in the second step, the resulting mutual interaction between circular orbits is expanded around a reference point. As usual, the resulting expansion is presented in the Fourier series form, where the force amplitudes are dependent on the semimajor axis, eccentricity and inclination, and the harmonic arguments are linear combinations of the mean longitude, longitude of pericenter and longitude of ascending node of each mass. The resulting new expansion is valid for arbitrary inclinations and semimajor axis ratios. In the case of mean motion resonant configuration, the disturbing function can be easily averaged to produce the analytical expansion of resonant disturbing function. Based on the analytical expansion, the Hamiltonian model of mean motion resonances is formulated, and the resulting analytical developments are applied to Jupiter’s inner and co-orbital resonances and Neptune’s exterior resonances. Analytical expansion is validated by comparing the analytical results with the associated numerical outcomes.

Hidden-charm tetraquarks with strangeness in the chiral quark model

The hidden-charm tetraquarks with strangeness, $c\bar{c}s\bar{q}$ $(q=u,\,d)$, in $J^P=0^+$, $1^+$ and $2^+$ are systematically investigated in the framework of real- and complex-scaling range of a chiral quark model, whose parameters have been fixed in advance describing hadron, hadron-hadron and multiquark phenomenology. Each tetraquark configuration, compatible with the quantum numbers studied, is taken into account; this includes meson-meson, diquark-antidiquark and K-type arrangements of quarks with all possible color wave functions in four-body sector. Among the different numerical techniques to solve the Schr\"odinger-like 4-body bound state equation, we use a variational method in which the trial wave function is expanded in complex-range Gaussian basis functions, which is characterized by its simplicity and flexibility. This theoretical framework has already been used to study different kinds of multiquark systems, such as the hidden-charm pentaquarks, $P^+_c$, and doubly-charmed tetraquarks, $T^+_{cc}$. The recently reported $Z_{cs}$ states by the BESIII and LHCb collaborations are generally compatible with either compact tetraquark or hadronic molecular resonance configurations in our investigation. Moreover, several additional exotic resonances are found in the mass range between 3.8 GeV and 4.6 GeV.

Shape-preserving atomic pulse amplifier

Propagation of a weak probe pulse through a Λ system in a resonant gain configuration is investigated. We employ the control field intensity that permits the amplification of probe pulse during propagation, without instability at two photon resonance. Posterior to amplification, a broadened probe pulse is obtained, which retains its initial pulse shape and travels at the speed of light in vacuum without experiencing any delay, absorption, and dispersion. The salient feature of this technique lies in the fact that in addition to preserving the initial pulse shape, it also ensures stable pulse propagation after amplification. It also works for arbitrary probe pulse shapes.

The ‘breaking the chains’ migration model for super-Earth formation: the effect of collisional fragmentation

ABSTRACT Planets between 1 and 4 R⊕ (Earth radius) with orbital periods <100 d are strikingly common. The migration model proposes that super-Earths migrate inwards and pile up at the disc inner edge in chains of mean motion resonances. After gas disc dispersal, simulations show that super-Earth’s gravitational interactions can naturally break their resonant configuration leading to a late phase of giant impacts. The instability phase is key to matching the orbital spacing of observed systems. Yet, most previous simulations have modelled collisions as perfect accretion events, ignoring fragmentation. In this work, we investigate the impact of imperfect accretion on the ‘breaking the chains’ scenario. We performed N-body simulations starting from distributions of planetary embryos and modelling the effects of pebble accretion and migration in the gas disc. Our simulations also follow the long-term dynamical evolution of super-Earths after the gas disc dissipation. We compared the results of simulations where collisions are treated as perfect merging events with those where imperfect accretion and fragmentation are allowed. We concluded that the perfect accretion is a suitable approximation in this regime, from a dynamical point of view. Although fragmentation events are common, only ∼10 per cent of the system mass is fragmented during a typical ‘late instability phase’, with fragments being mostly reacreted by surviving planets. This limited total mass in fragments proved to be insufficient to alter qualitatively the final system dynamical configuration – e.g. promote strong dynamical friction or residual migration – compared to simulations where fragmentation is neglected.

Experimental investigation of dynamic lingual organ pipes with blown open tongue.

This paper presents the experimental examination of an alternative lingual organ pipe construction that uses a free tongue which, in contrast with traditional lingual organ pipes, operates in a blown open manner. A possible advantage of the construction is that it can enable changing the windchest pressure and thus, achieving an extended dynamic range while keeping a constant pitch. Three experimental pipes with diverse resonator shapes are investigated in various setups. The three pipes also demonstrate the variety of timbres obtainable by different configurations of tongues and resonators. The analysis of the measurement results shows that the pipes exhibit a very good stability of the fundamental frequency and can have a dynamic range of 15 dB. At the same time, the timbre of the sound is found to change significantly as the windchest pressure is increased. Experiments performed with damping the resonator reveal the working principle of the tongue-resonator coupling in the alternative construction. Several sound recordings are presented as multimedia file attachments enabling the subjective comparison of the pipe sounds.

Effects of Spin–Orbit Resonances and Tidal Heating on the Inner Edge of the Habitable Zone

Abstract Much attention has been given to the climate dynamics and habitable boundaries of synchronously rotating planets around low mass stars. However, other rotational states are possible, including spin–orbit resonant configurations, particularly when higher eccentricity orbits can be maintained in a system. Additionally, the oscillating strain as a planet moves from periastron to apoastron results in friction and tidal heating, which can be an important energy source. Here, we simulate the climate of ocean-covered planets near the inner edge of the habitable zone around M to solar stars with the NASA GISS ROCKE-3D general circulation model, and leverage the planetary evolution software package, VPLanet, to calculate tidal heating rates for Earth-sized planets orbiting 2600 and 3000 K stars. This study is the first to use a 3D general circulation model that implements tidal heating to investigate habitability for multiple resonant states. We find that for reference experiments without tidal heating, the resonant state has little impact on the radial position of the inner edge because for a given stellar flux, higher-order states tend to be warmer than synchronous rotators, but for a given temperature, have drier upper atmospheres. However, when strong tidal heating is present, the rotational component implies a strong dependence of habitable conditions on the system evolution and rotational state. Since tidal and stellar heating both decrease rapidly with orbital distance, this results in a compact orbital width separating temperate and uninhabitable climates. We summarize these results and also compare ROCKE-3D to previously published simulations of the inner edge.

Application of the Shannon entropy in the planar (non-restricted) four-body problem: the long-term stability of the Kepler-60 exoplanetary system

ABSTRACT In this paper, we present an application of the Shannon entropy in the case of the planar (non-restricted) four-body problem. Specifically, the Kepler-60 extrasolar system is being investigated with a primary interest in the resonant configuration of the planets that exhibit a chain of mean-motion commensurabilities with the ratios 5:4:3. In the dynamical maps provided, the Shannon entropy is utilized to explore the general structure of the phase space, while, based on the time evolution of the entropy, we also determine the extent and rate of the chaotic diffusion as well as the characteristic times of stability for the planets. Two cases are considered: (i) the pure Laplace resonance when the critical angles of the two-body resonances circulate and that of the three-body resonance librates; and (ii) the chain of two two-body resonances when all the critical angles librate. Our results suggest that case (ii) is the more favourable configuration, but we state too that, in either case, the relevant resonance plays an important role in stabilizing the system. The derived stability times are no shorter than 108 yr in the central parts of the resonances.

A Precisely‐Controlled Multichannel Phononic Crystal Resonant Cavity

AbstractDesigning multichannel phononic crystal (PnC) resonant cavities working at certain frequencies is highly nontrivial because the defect band location within the band gap must be precisely located. This paper discloses a new methodology of the topological design for the precisely‐controlled PnC resonant cavity. A two‐stage topological design strategy is proposed to determine the frequency ranges of the forbidden and defect bands successively. Complicated topologies of the supercell are represented only with dozens of design variables based on material‐field series expansion model and can be optimized with a gradient‐free optimization algorithm. Different PnC resonant cavity configurations that are difficult to obtain through traditional design methods are realized through the proposed strategy. A multichannel energy harvester is thus designed with the optimized supercell configurations. The device demonstrates a high localization effect (>300%), high frequency resolution of the incident wave (≈0.2 kHz), and a 2 mW power output.

Quintuple‐mode wideband bandpass filter based on stub‐loaded circular resonator

In this paper, novel compact wideband filters have been implemented using a stub-loaded microstrip resonator based on a circular open-loop configuration for the first time. To offer an alternative wideband filter configuration, the quadruple−/quintuple-mode wideband bandpass filters (BPFs) using stub-loaded circular microstrip resonator (SLCMR) and parallel-coupled microstrip line (PCML) feed configuration are proposed. They are realized by employing a single open stub and two open stubs, respectively. A half-wavelength λ / 2 circular microstrip resonator (CMR) loaded with two open stubs excites three resonant modes, while the one with a single stub produces two resonant modes. One of the modes is odd-mode generated by a λ / 2 CMR, the others are even-modes excited by the two loading stubs. The PCML with enhanced input/output (I/O) coupling degree excites also two modes in the passband. Two loading stubs not only creates transmission poles in the passband, they also create two transmission zeros in the lower and upper stopbands. The quadruple−/quintuple-mode wideband BPFs with fractional bandwidths FBW of 60% and 62% are successfully realized by using the SLCMR and PCML feed configuration together. Both filters are designed, fabricated, and tested where excellent agreement between simulated and measured results is observed.

A Bayesian neural network predicts the dissolution of compact planetary systems

We introduce a Bayesian neural network model that can accurately predict not only if, but also when a compact planetary system with three or more planets will go unstable. Our model, trained directly from short N-body time series of raw orbital elements, is more than two orders of magnitude more accurate at predicting instability times than analytical estimators, while also reducing the bias of existing machine learning algorithms by nearly a factor of three. Despite being trained on compact resonant and near-resonant three-planet configurations, the model demonstrates robust generalization to both nonresonant and higher multiplicity configurations, in the latter case outperforming models fit to that specific set of integrations. The model computes instability estimates up to [Formula: see text] times faster than a numerical integrator, and unlike previous efforts provides confidence intervals on its predictions. Our inference model is publicly available in the SPOCK (https://github.com/dtamayo/spock) package, with training code open sourced (https://github.com/MilesCranmer/bnn_chaos_model).

Cascaded microring resonator configuration with inbuilt tapered regions for simultaneous detection of assorted nanoparticles

Fast and accurate detection of nanoparticles (NP) has always been challenging due to the weak interaction of nanoparticles with the transducing signal. Moreover, detecting nanoparticles of different sizes and types mixed in a matrix adds more difficulty. In this work, we propose an integrated on-chip photonic platform that can detect a single nanoparticle. The proposed device comprises two parallel-coupled microring resonators where a small region in the noncoupled arms of the resonator has been tapered. Tapered regions intensify the evanescent field strength by many folds, which improves light–matter interaction, resulting in better sensitivity. Finite difference time domain simulations reveal the splitting of a resonant mode in the presence of a gold nanoparticle (AuNP) of radius 100 nm, whereas in the case of dielectric NP, broadening in linewidth is observed. The proposed approach has the unique capability to detect various sizes and types of NP simultaneously, including dielectric nanoparticles. Therefore, the proposed architecture may play a pivotal role in the simultaneous quantification and identification of biological objects such as novel viruses, bacteria, and proteins.

Modelling and Analysis of Quadruple Asymmetrical Optical Micro-Ring Resonator for Biosensing Application

In this paper, modelling of an asymmetrical micro-ring resonator and its performance as an optical filter and optical sensor is analysed. Quadruple asymmetrical optical micro-ring resonator (QAOMRR) is mathematically modelled in Z-domain using delay line signal processing technique. The transmittance of the configuration is calculated using signal flow graph method. Vernier principle method is applied to achieve larger free spectral range (FSR). Also, the proposed QAOMRR in silicon-on-insulator (SOI) platform is used for biochemical sensing. The proposed QAOMRR offers a FSR of 3.155 THZ and Q- factor of 3875 as well as provide significant shift in resonant wavelength whenever any different analyte is present in biomolecules. Field investigation of the proposed QAOMRR is done using Finite Difference Time Domain (FDTD) method. The directional couplers are designed using FDTD simulations. The proposed method will be extremely useful for modelling analysis and design of different micro optical asymmetrical ring resonator configurations.

25 W continuous-wave Yb:LiLuF4 single-crystal-fiber laser oscillator

We present the first demonstration of a solid-state laser oscillator based on a Yb-doped, birefringent single crystal fiber grown by the micro-pulling-down method. Pumping a 42-mm-long, 2%-at. Yb3+:LiLuF4 crystal with a 105-W maximum power fiber coupled laser diode, we obtained a maximum output power of 10.4 W, with diffraction limited beam quality (M2<1.1), in a simple plane-concave resonator. By modifying the resonator layout to increase the laser efficiency, we obtained output power up to 25 W, with still fairly good beam quality (M2≃2). Thermal lensing effect and laser intrinsic slope efficiency and losses were characterized in both resonator configurations.

Synthesis and design of filters and multiplexers with acoustic transversal topology

AbstractThe novel acoustic transversal topology has demonstrated to be a potential candidate for the development of the next generation of communication filters. The major asset of this topology is its capacity to achieve any filter response without the detriment of limited electro-acoustic coupling. Additionally, this topology prompts for an easy connection of different filters to create multiband and multiplexing responses. This study recalls and further details on the design of multiplexers based on transversal topology using bulk acoustic wave (BAW) or surface acoustic wave (SAW) resonators. An important practical aspect of this topology is the need of a BALUN stage at one port of the filter.The use of the transversal topology is then applied to another type of acoustic resonator configuration, coupled resonator filter (CRF). Such a resonator configuration offers control over the phase of each transversal path, allowing us to eliminate the BALUN stage. CRF resonators are modeled by means of a different circuit model than BAW or SAW, which calls for a new synthesis procedure. This paper describes the synthesis approach and circuit transformation for the development of multiplexers based on the transversal arrangement of the CRF resonators. An example of a fully simulated 9-plexer is provided to verify this procedure.

The exomoon corridor for multiple moon systems

ABSTRACT The so-called ‘exomoon corridor’ is a potentially powerful new tool for identifying possible exomoon hosts, enabled by the observation that fully half of all planets hosting an exomoon will exhibit transit timing variation (TTV) periodicities of 2–4 epochs. One key outstanding problem in the search for exomoons, however, is the question of how well the methods we have developed under the single moon assumption extend to systems with multiple moons. In this work, we use N-body simulations to examine the exomoon corridor effect in the more general case of N ≥ 1 moons, generating realistic TTVs produced by satellite systems more akin to those seen in the outer Solar System. We find that indeed the relationship does hold for systems with up to 5 moons in both resonant and non-resonant chain configurations. Our results suggest an observational bias against finding systems with large numbers of massive moons; as the number of moons increases, total satellite mass ratios are generally required to be significantly lower in order to maintain stability, or architectures must be more finely tuned to survive. Moons produced in impact or capture scenarios may therefore dominate early detections. Finally, we examine the distribution of TTV periods measured for a large number of Kepler objects of interest (KOIs) and find the same characteristic exomoon corridor distribution in several cases. This could be dynamical evidence for an abundance of moons in the field, though we caution against strong inferences based on this result.

Impact of intragrain spin wave reflections on nanocontact spin torque oscillators

We investigate the origin of the experimentally observed varying current-frequency nonlinearity of the propagating spin wave mode in nano-contact spin torque oscillators. Nominally identical devices with 100 nm diameter are characterized by electrical microwave measurements and show large variation in the generated frequency as a function of drive current. This quantitative and qualitative device-to-device variation is described in terms of continuous and discontinuous nonlinear transitions between linear current intervals. The thin film grain microstructure in our samples is determined using atomic force and scanning electron microscopy to be on the scale of 30 nm. Micromagnetic simulations show that the reflection of spin waves against the grain boundaries results in standing wave resonance configurations. For a simulated device with a single artificial grain, the frequency increases linearly with the drive current until the decreased wavelength eventually forces another spin wave anti-node to be formed. This transition results in a discontinuous step in the frequency versus current relation. Simulations of complete, randomly generated grain microstructures additionally shows continuous nonlinearity and a resulting device-to-device variation in frequency that is similar to the experimental levels. The impact of temperature from 4 K to 300 K on the resonance mode-transition nonlinearity and frequency noise is investigated using simulations and it is found that the peak levels of the spectral linewidth as a function of drive current agrees quantitatively with typical levels found in experiments at room temperature.

Magnetic induction device for nanoparticles heating at frequency > 500 kHz

Treatment with magnetic induction hyperthermia can be complementary by raising the temperature in cell clusters above 42 ∘C, this procedure increasing the effectiveness of treatments for the elimination of cancer cells based on drugs. A magnetic induction device working in selectable modules of frequencies > 500 kHz is presented, it was developed and constructed for transfer heat in a selected biological tissue. An LC parallel resonant circuit configuration was used with an inverter coupled to a power supply as an auto-resonator and the oscillation frequency depends on the capacitor bank to generate a phased sine signal in the oscillating signal in the LC tank circuit. It works with switchable modules that operate in different frequencies, among 85 kHz and 900 kHz which makes it completely autonomous and portable, this selection of work frequencies is the main contribution of this equipment. This device generating a magnetic field from 0.44 mT to 5.11 mT. So, the use of a self-resonator inverter allows operating without requiring an external signal generator for tuning the different frequencies, coupled with the incorporation of a cooling system embedded in the same device, which makes no external complimentary devices required. Finally, it is highlighted that the frequency range presented in this work is higher than those reported by other authors, which is below 500 kHz.

Formation of planetary systems by pebble accretion and migration

At least 30% of main sequence stars host planets with sizes of between 1 and 4 Earth radii and orbital periods of less than 100 days. We useN-body simulations including a model for gas-assisted pebble accretion and disk–planet tidal interaction to study the formation of super-Earth systems. We show that the integrated pebble mass reservoir creates a bifurcation between hot super-Earths or hot-Neptunes (≲15M⊕) and super-massive planetary cores potentially able to become gas giant planets (≳15M⊕). Simulations with moderate pebble fluxes grow multiple super-Earth-mass planets that migrate inwards and pile up at the inner edge of the disk forming long resonant chains. We follow the long-term dynamical evolution of these systems and use the period ratio distribution of observed planet-pairs to constrain our model. Up to ~95% of resonant chains become dynamically unstable after the gas disk dispersal, leading to a phase of late collisions that breaks the original resonant configurations. Our simulations naturally match observations when they produce a dominant fraction (≳95%) of unstable systems with a sprinkling (≲5%) of stable resonant chains (the Trappist-1 system represents one such example). Our results demonstrate that super-Earth systems are inherently multiple (N≥ 2) and that the observed excess of single-planet transits is a consequence of the mutual inclinations excited by the planet–planet instability. In simulations in which planetary seeds are initially distributed in the inner and outer disk, close-in super-Earths are systematically ice rich. This contrasts with the interpretation that most super-Earths are rocky based on bulk-density measurements of super-Earths and photo-evaporation modeling of their bimodal radius distribution. We investigate the conditions needed to form rocky super-Earths. The formation of rocky super-Earths requires special circumstances, such as far more efficient planetesimal formation well inside the snow line, or much faster planetary growth by pebble accretion in the inner disk. Intriguingly, the necessary conditions to match the bulk of hot super-Earths are at odds with the conditions needed to match the Solar System.