Resonator Configuration Research Articles

Stabilized 30 µJ dissipative soliton resonance laser source at 1064nm.

We demonstrate the first successful stabilization of a dissipative soliton resonance (DSR) mode-locked (ML) laser source using straightforward techniques. Our setup employed a figure-8 (F8) resonator configuration and a nonlinear optical loop mirror (NOLM) to achieve stable mode-locking, generating 1064nm rectangular pulses with a 3 ns duration at a repetition frequency of ~ 1MHz. The pulses were boosted in an all-fiber amplifier chain and reached 30 µJ and 10kW peak power per pulse at 30W average output power. We addressed a critical gap in the literature by actively stabilizing key DSR pulse parameters: average output power (improved by a factor of 51), pulse repetition frequency (improved by 7583 using cross-phase modulation for synchronization), and pulse duration (improved by a factor of ~ 4). Additionally, we included a numerical analysis to explore the pulse formation mechanisms in DSR ML lasers working in a F8 configuration. Our findings show that non-complex all-in-fiber DSR ML lasers can reliably produce high-energy pulses with stable, repeatable parameters, making them suitable for future applications e.g. in nonlinear frequency conversion, laser micromachining, or LIDAR.

The Prevalence of Resonance Among Young, Close-in Planets

Multiple planets undergoing disk migration may be captured into a chain of mean-motion resonances with the innermost planet parked near the disk’s inner edge. Subsequent dynamical evolution may disrupt these resonances, leading to the nonresonant configurations typically observed among Kepler planets that are Gyr old. In this scenario, resonant configurations are expected to be more common in younger systems. This prediction can now be tested, thanks to recent discoveries of young planets, in particular those in stellar clusters, by NASA’s TESS mission. We divided the known planetary systems into three age groups: young (<100 Myr old), adolescent (0.1–1 Gyr old), and mature (>1 Gyr old). The fraction of neighboring planet pairs having period ratios within a few percent of a first-order commensurability (e.g., 4:3, 3:2, or 2:1) is 70% ± 15% for young pairs, 24% ± 8% for adolescent pairs, and 15% ± 2% for mature pairs. The fraction of systems with at least one nearly commensurable pair (either first- or second-order) is 86% ± 13% among young systems, 38% ± 12% for adolescent systems, and 23% ± 3% for mature systems. First-order commensurabilities prevail across all age groups, with an admixture of second-order commensurabilities. Commensurabilities are more common in systems with high planet multiplicity and low mutual inclinations. Observed period ratios often deviate from perfect commensurability by ∼1% even among young planets, too large to be explained by resonant repulsion with equilibrium eccentricity tides. We also find that super-Earths in the radius gap (1.5–1.9R ⊕) are less likely to be near-resonant (11.9% ± 2.0%) compared to Earth-sized planets (R p < 1R ⊕; 25.3% ± 4.4%) or mini-Neptunes (1.9R ⊕ ≤ R p < 2.5R ⊕; 14.4% ± 1.8%).

Sympathetic Mechanism for Vibrational Condensation Enabled by Polariton Optomechanical Interaction.

We demonstrate a macrocoherent regime in exciton-polariton systems, where nonequilibrium polariton Bose-Einstein condensation coexists with macroscopically occupied vibrational states. Strong exciton-vibration coupling induces an effective optomechanical interaction between cavity polaritons and vibrational degrees of freedom of molecules, leading to vibrational amplification in a resonant blue-detuned configuration. This interaction provides a sympathetic mechanism to achieve vibrational condensation with potential applications in cavity-controlled chemistry, nonlinear, and quantum optics.

Single-Ended Surface Acoustic Wave Pressure Resonators

Abstract Surface acoustic wave (SAW) sensors exhibit advantageous attributes for pressure detection, including compact dimensions, cost-effectiveness, facile integration, elevated sensitivity, and a high quality factor (Q value). In this study, the single-ended resonant configuration of SAW pressure sensing element based on ST-X cut quartz was simulated and fabricated. The influence of the interdigitated transducer (IDT) and applied pressure on the resonance frequency of SAW were simulated and analyzed. The designed phase velocity (3159.344 m/s) without IDT is closest to the theoretical phase velocity (3158 m/s) of SAW propagation in the substrate, and the relative error is about 0.043%. The designed phase velocity of SAW dropped to 3149.198 m/s due to the loading of the IDT mass. With an increase in applied pressure from 0 to 350 kPa, the resonance frequency of the SAW decreases from 157.05 to 154.02 MHz, yielding a maximum linear pressure sensitivity of approximately 8.6 kHz/kPa. The measured center frequencies of the fabricated single-ended SAW devices are predominantly clustered around 157 MHz, exhibiting a deviation of 0.46 MHz from the simulated results. The present work establishes a foundation for subsequent experimental investigations into pressure sensing.

Ring-assisted, racetrack, and Mach-Zehnder modulator: which one offers the lowest voltages and chirp-free operation?

This study presents a comparison between resonant and non-resonant electro-optical modulator configurations. The focus lies on finding the configuration with the highest modulation amplitude at the lowest drive voltage while achieving a large electro-optical bandwidth. It is found that the ring-assisted Mach-Zehnder modulator (RaMZM) offers chirp-free and resonantly enhanced modulation without bandwidth limitations imposed by the ring. In contrast, a racetrack modulator (RTM) offers resonant enhancement at the cost of a chirped modulated signal and with a bandwidth limitation. The traditional non-resonant Mach-Zehnder modulator (MZM) configuration requires higher modulation voltages while offering chirp-free operation with a flat frequency response. The RaMZM, therefore, looks like an ideal candidate for encoding information in backbone networks where small modulation voltages and perfect control over the phase of a signal are needed. The results are supported by experiments that show driverless plasmonic modulation at 220 GBaud 2PAM, 160 GBaud 4PAM and 100 GBaud 8PAM with record low peak voltages of 0.5 V.

Dual-tube MEMS-based spectrophone for sub-ppb mid-IR photoacoustic gas detection

Nowadays, the scientific community and industry are increasingly pressed to provide solutions for developing compact and highly-performing trace-gas sensors for several applications of crucial importance, such as environmental monitoring or medical diagnostics. In this context, this work describes a novel configuration, making use of a mid-IR spectrophone combining the compactness of a photo-acoustic setup, a non-conventional micro-electro-mechanical (MEMS) acousto-to-voltage transducer, and the sensitivity enhancement given by a cost-effective and easy-to-build dual-tube resonator configuration. In the optimal condition of sample pressure, the system developed in this work can achieve a minimum detection limit (MDL) equal to 0.34 ppb when averaging up to 10 s. Compared with previous literature of single-pass photoacoustic-based sensors for N2O, this corresponds to a significant improvement both for the achieved normalized noise equivalent absorption coefficient (NNEA) equal to 1.41 × 10−9 cm−1WHz−1/2, and for a Noise-Equivalent-Concentration (NEC) of 1 ppb obtained at 1 s of averaging time.

Partially embedded metabarrier to suppress surface waves in granular mediaa).

The gravity-induced depth-dependent elastic properties of a granular half-space result in multiple dispersive surface modes and demand the consideration of material heterogeneity in metabarrier designs to suppress surface waves. Numerous locally resonant metabarrier configurations have been proposed in the literature to suppress Rayleigh surface waves in homogeneous media, with little focus on extending the designs to a heterogeneous half-space. In this work, a metabarrier comprising partially embedded rod-like resonators to suppress the fundamental dispersive surface wave modes in heterogeneous granular media known as first order PSV (PSV1; where P is the longitudinal mode and SV is the shear-vertical mode) and second order PSV (PSV2) is proposed. The unit-cell dispersion analysis, together with an extensive frequency-domain finite element analysis, reveals preferential hybridization of the PSV1 and PSV2 modes with the longitudinal and flexural resonances of the resonators, respectively. The presence of the cutoff frequency for the longitudinal-resonance hybridized mode facilitates straightforward suppression of the PSV1 mode, while PSV2 mode suppression is possible by tailoring the hybridized flexural resonance modes. These PSV1 and PSV2 bandgaps are realized experimentally in a granular testbed comprising glass beads by embedding 3D-printed resonator rods. Also explored are novel graded metabarriers capable of suppressing both PSV1 and PSV2 modes over a broad frequency range for potential applications in vibration control and seismic isolation.

Oxygen-defective electrostrictors for soft electromechanics.

Electromechanical metal oxides, such as piezoceramics, are often incompatible with soft polymers due to their crystallinity requirements, leading to high processing temperatures. This study explores the potential of ceria-based thin films as electromechanical actuators for flexible electronics. Oxygen-deficient fluorites, like cerium oxide, are centrosymmetric nonpiezoelectric crystalline metal oxides that demonstrate giant electrostriction. These films, deposited at low temperatures, integrate seamlessly with various soft substrates like polyimide and PET. Ceria thin films exhibit remarkable electrostriction (M33 > 10-16 m2 V-2) and inverse pseudo-piezo coefficients (e33 > 500 pmV-1), enabling large displacements in soft electromechanical systems. Our study explores resonant and off-resonant configurations in the low-frequency regime (<1 kHz), demonstrating versatility for three-dimensional and transparent electronics. This work advances the understanding of oxygen-defective metal oxide electromechanical properties and paves the way for developing versatile and efficient electromechanical systems for applications in biomedical devices, optical devices, and beyond.

Resonant and Ultra-short-period Planet Systems Are at Opposite Ends of the Exoplanet Age Distribution

Exoplanet systems are thought to evolve on secular timescales over billions of years. This evolution is impossible to directly observe on human timescales in most individual systems. While the availability of accurate and precise age inferences for individual exoplanet host stars with ages τ in the interval 1 Gyr ≲ τ ≲ 10 Gyr would constrain this evolution, accurate and precise age inferences are difficult to obtain for isolated field dwarfs like the host stars of most exoplanets. The Galactic velocity dispersion of a thin-disk stellar population monotonically grows with time, and the relationship between age and velocity dispersion in a given Galactic location can be calibrated by a stellar population for which accurate and precise age inferences are possible. Using a sample of subgiants with precise age inferences, we calibrate the age–velocity dispersion relation in the Kepler field. Applying this relation to the Kepler field’s planet populations, we find that Kepler-discovered systems plausibly in second-order mean-motion resonances have 1 Gyr ≲ τ ≲ 2 Gyr. The same is true for systems plausibly in first-order mean-motion resonances, but only for systems likely affected by tidal dissipation inside their innermost planets. These observations suggest that many planetary systems diffuse away from initially resonant configurations on secular timescales. Our calibrated relation also indicates that ultra-short-period (USP) planet systems have typical ages in the interval 5 Gyr ≲ τ ≲ 6 Gyr. We propose that USP planets tidally migrated from initial periods in the range 1 day ≲ P ≲ 2 days to their observed locations at P < 1 day over billions of years and trillions of cycles of secular eccentricity excitation and inside-planet damping.

Photo-dynamical characterisation of the TOI-178 resonant chain

Context. The TOI-178 system consists of a nearby, late-K-dwarf with six transiting planets in the super-Earth to mini-Neptune regime, with radii ranging from to 2.9 R⊕ and orbital periods between 1.9 and 20.7 days. All the planets, but the innermost one, form a chain of Laplace resonances. The fine-tuning and fragility of such orbital configurations ensure that no significant scattering or collision event has taken place since the formation and migration of the planets in the protoplanetary disc, thereby providing important anchors for planet formation models. Aims. We aim to improve the characterisation of the architecture of this key system and, in particular, the masses and radii of its planets. In addition, since this system is one of the few resonant chains that can be characterised by both photometry and radial velocities, we propose to use it as a test bench for the robustness of the planetary mass determination with each technique. Methods. We performed a global analysis of all the available photometry from CHEOPS, TESS and NGTS, and radial velocity from ESPRESSO, using a photo-dynamical modelling of the light curve. We also tried different sets of priors on the masses and eccentricity, as well as different stellar activity models, to study their effects on the masses estimated by transit-timing variations (TTVs) and radial velocities (RVs). Results. We demonstrate how stellar activity prevents a robust mass estimation for the three outer planets using radial velocity data alone. We also show that our joint photo-dynamical and radial velocity analysis has resulted in a robust mass determination for planets c to 𝑔, with precision of ~ 12% for the mass of planet c, and better than 10% for planets d to 𝑔. The new precisions on the radii range from 2 to 3%. The understanding of this synergy between photometric and radial velocity measurements will be valuable for the PLATO mission. We also show that TOI-178 is indeed currently locked in the resonant configuration, librating around an equilibrium of the chain.

The Solar System could have formed in a low-viscosity disc: A dynamical study from giant planet migration to the Nice model

Context. In the context of low-viscosity protoplanetary discs (PPDs), the formation scenarios of the Solar System should be revisited. In particular, the Jupiter-Saturn pair has been shown to lock in the 2:1 mean motion resonance while migrating generally inwards, making the Grand Tack scenario impossible. Aims. We explore what resonant chains of multiple giant planets can form in a low-viscosity disc, and whether these configurations can evolve into forming the Solar System in the post gas disc phase. Methods. We used hydrodynamical simulations with the code FARGOCA to study the migration of the giant planets in a disc with viscosity parameter of α = 10−4. After a transition phase to a gas-less configuration, we studied the stability of the obtained resonant chains through their interactions with a disc of leftover planetesimals by performing N-body simulations using rebound. Results. The gaps opened by giant planets are wider and deeper for lower viscosity, reducing the damping effect of the disc. Thus, when planets enter a resonance, the resonant angle remains closer to circulation, making the chain weaker. Exploring numerous configurations, we found five stable resonant chains of four or five planets. In a thin (cold) PPD, the four giant planets revert their migration and migrate outwards. After disc dispersal, under the influence of a belt of planetesimals, some resonant chains undergo an instability phase while others migrate smoothly over a billion years. For three of our resonant chains, about ~1% of the final configurations pass the four criteria to fit the Solar System. The most successful runs are obtained for systems formed in a cold PPD with a massive planetesimal disc. Conclusions. This work provides a fully consistent study of the dynamical history of the Solar System’s giant planets, from the protoplanetary disc phase up to the giant planet instability. Although building resonant configurations is difficult in low-viscosity discs, we find it possible to reproduce the Solar System from a cold, low-viscosity protoplanetary disc.

Ultra-thin optical power converters based on Gires–Tournois resonator configuration operating in high-order modes

In this study, we propose a strategy to construct high-performance ultra-thin optical power converters (OPCs) based on Gires–Tournois resonator configurations operating in high-order modes. Despite reducing the absorber thickness by 5.8 to 8.1 times, the proposed ultra-thin OPCs exhibit the same (comparable) energy absorption characteristic and demonstrate superior electrical performance compared to a thick OPC. It is revealed that such high absorption effects originated from the excitation of optical asymmetric Fabry–Perot-type high-order inference resonance modes and the electrical performance enhancement can be attributed to the reduction of the absorber thickness.

High average power (105 W) Fe:ZnSe laser pumped by radiation of laser diode side-pumped Er:YAG lasers.

A high average power re-frequency operation Fe:ZnSe laser using laser diode side-pumped free-running Er:YAG lasers as activating sources is presented. Two pieces of subsurface layer doped Fe:ZnSe polycrystal are adoptive in a reflective resonator configuration and face-cooled by liquid nitrogen. A maximal Fe:ZnSe laser power of 105 W at a wavelength of 4.1 μm is achieved upon pumping by ten home-made Er:YAG lasers with fiber coupled output working at a frequency of 250 Hz and a pulse duration of ∼420 μs. Corresponding to the maximum Fe:ZnSe laser power, the optical-optical efficiency and slope efficiency with respect to the absorbed pump power are 43% and 44% respectively. The beam quality factor M2 is measured to be 3.4. To the best of our knowledge, it is the highest output average power of an Fe:ZnSe laser reported.

Resonant chains in triple-planet systems

The mean motion resonance is the most important mechanism that may dominate the dynamics of a planetary system. In a multi-planetary system consisting of $N planets, the planets may form a resonant chain when the ratios of orbital periods of planets can be expressed as the ratios of small integers $T_1: T_2: :T_N=k_1: k_2: k_N$. Due to the high degree of freedom, the motion in such systems could be complex and difficult to depict. In this paper, we investigate the dynamics and possible formation of the resonant chain in a triple-planet system. We defined the appropriate Hamiltonian for a three-planet resonant chain and numerically averaged it over the synodic period. The stable stationary solutions -- apsidal corotational resonances (ACRs) -- of this averaged system, corresponding to the local extrema of the Hamiltonian function, can be searched out numerically. The topology of the Hamiltonian around these ACRs reveals their stabilities. We further constructed the dynamical maps on different representative planes to study the dynamics around the stable ACRs, and we calculated the deviation ($ of the resonant angle in the evolution from the uniformly distributed values, by which we distinguished the behaviour of critical angles. Finally, the formation of the resonant chain via convergent planetary migration was simulated and the stable configurations associated with ACRs were verified. We find that the stable ACR families arising from circular orbits always exist for any resonant chain, and they may extend to a high eccentricity region. Around these ACR solutions, regular motion can be found, typically in two types of resonant configurations. One is characterised by libration of both the two-body resonant angles and the three-body Laplace resonant angle, and the other by libration of only two-body resonant angles. The three-body Laplace resonance does not seem to contribute to the stability of the resonant chain much. The resonant chain can be formed via convergent migration, and the resonant configuration evolves along the ACR families to eccentric orbits once the planets are captured into the chain. Ideally, our methods introduced in this paper can be applied to any resonant chain of any number of planets at any eccentricity.

Surface Plasmon-Coupled Directional Emission Enhanced Raman Scattering Based on Waveguide Coupling Surface Plasmon Resonance Configuration

Surface Plasmon-Coupled Directional Emission Enhanced Raman Scattering Based on Waveguide Coupling Surface Plasmon Resonance Configuration

Design, fabrication, and evaluation of a novel highly sensitive tuning fork pressure sensor for precise liquid level measurement

This article investigates the under-explored potential of utilizing a thin stainless-steel diaphragm coupled with a quartz tuning fork sensor for liquid depth measurements. The focus is on monitoring molten salt fluid levels in nuclear reactors and concentrated solar power systems. Addressing a literature gap, the research explores cantilever-type configurations of a double-ended quartz tuning fork resonator, with a no-load resonance frequency of 17.37 kHz, on thin stainless-steel diaphragms for fluid depth measurement at room temperature. As the fluid depth increases, hydro-static pressure acting on a 20 μm diaphragm causes deflection, bending a tuning fork. The resulting change in resonance frequency correlates with fluid depth. Experimental setups assess the tuning fork’s sensitivity to strain and bending, revealing strain sensitivity of 7.83 Hz/μ strain (450.78 ppm/μ strain) and bending sensitivity of 0.09 Hz/μm (5.18 ppm/μm). The pressure sensor assembly, tested in a water tank, exhibits a sensitivity of −0.28 Hz/mm (−16.12 ppm/mm) in a single cantilever-type configuration. Despite a limited linear range, it effectively measures water depth changes as small as 0.7 mm. Exploring a double cantilever-type configuration yields a sensitivity of 0.07 Hz/mm (4.03 ppm/mm) with a broader linear range. The article discusses the reasons for opposite sensitivity and highlights the advantages of each configuration. Beyond molten salt level monitoring, the technology’s applications may extend to fluid depth and pressure measurements in industrial and domestic settings.

Compact maze-shaped meta resonator for high-sensitive S-band low permittivity characterization

This paper proposed a compact, high-sensitive S-band microwave sensor for low permittivity characterization. The proposed microwave sensor is inspired by a metamaterials-based maze-shaped split-ring resonator (MS-SRR) configuration, and its overall dimensions are 25 mm × 20 mm × 0.79 mm. The unloaded state of the proposed sensor achieved two robust band-stop notches in its transmission response at 2.77 GHz and 3.08 GHz, respectively. These distinctive features enable the real-time measurement of permittivity in low-permittivity materials. The MS-SRR configuration accomplished strong electric-field intensity, which increased the interaction between the field and testing material, resulting in a highly sensitive measurement. A sensitivity of 11.91% is observed for the first resonance peak and 12.01% for the second peak within the permittivity range from 1 to 2.0. Moreover, the proposed sensor is also competent in measuring the permittivity range between 3 and 10 with a sensitivity of 9.47%–4.93% for the first peak and 9.57%–4.83% for the second peak. The resonance frequency shifting by the influence of material under test (MUT) is presented as a function of permittivity using a regression model. The simulated, measured and formulated results agree well. Finally, the proposed compact and high-sensitive microwave sensor holds promise for low permittivity characterization applications.

Detunable wireless resonator arrays for TMJ MRI: A comparative study

Temporomandibular Joint Magnetic Resonance Imaging (TMJ MRI) is crucial for diagnosing temporomandibular disorders (TMDs). This study advances the use of inductively coupled wireless coils to enhance imaging quality in TMJ MRI. After investigating multiple wireless resonator configurations, including a 1-loop design with a loop diameter of 9 cm, a 2-loop design with each loop having a diameter of 7 cm, and a 3-loop design with each loop having a diameter of 5 cm, our findings indicate that the 3-loop configuration achieves the optimal signal-to-noise ratio (SNR), surpassing other wireless arrays. Bilateral deployment of wireless coils further amplifies SNR, enabling superior visualization of TMJ structures, particularly with the 3-loop design. This cost-effective and comfortable solution, featuring a detunable design, eliminates the need for system parameter adjustments. The study indicates broad adaptability across MRI platforms, enhancing TMJ imaging for routine clinical diagnostics of TMDs.

An Analysis of Split-Ring Resonators and Potential Barcode Application

This paper presents an analysis of various split-ring resonator (SRR) configurations coupled with coplanar waveguides (CPW). Three distinct resonant structures are presented, namely, the S-shaped split-ring resonator (S-SRR), the conventional split-ring resonator (SRR), and a pair of SRR. Among the examined resonant structures, it is observed that the S-SRR exhibits the smallest electrical size with the corresponding resonant frequency of 1.37 GHz, while the conventional SRR has the largest electrical size with the corresponding resonant frequency of 3.34 GHz. On the other hand, the resonant frequency of a dual SRR is 2.37 GHz. However, the transmission coefficient of a dual SRR is -11.43 dB, which is higher than S-SRR (-10.02 dB) and SRR (-8.18 dB). Furthermore, this study extends the analysis between a square dual SRR and a circular dual SRR with retained area. The square SRR demonstrates a lower resonance frequency (2.23 GHz) relative to its circular counterpart (2.37 GHz). The comparison also shows that the transmission coefficient of the square configuration is -13.88 dB, which is higher than its circular counterpart (-11.43 dB). The realization of a barcode application is achieved by loading multiple S-shaped split ring resonators (S-SRRs) with varying geometric parameters adjacently onto the transmission line. By individually rotating each of these S-SRRs, it becomes possible to alter the notch magnitude, thereby positioning it within a specific designated range corresponding to a particular code. In the case of a configuration involving rotations of (0°, 45°, 90°, 0°, 45°, 90°), this approach results in the creation of a barcode denoted as "100 010 000 100 011 000". This methodology enables the encoding of information in the form of distinctive resonant responses, providing a versatile and compact means of realizing barcode applications.

Miniaturized computational spectrometer based on two-photon absorption

On-chip spectrometers hold significant promise in the development of laboratory-on-a-chip applications. However, the spectrometers usually require extra on-chip or off-chip photodetectors (PDs) to sense optical signals, resulting in increased footprints and costs. In this paper, we address this issue by proposing a fully on-chip spectrometer based on two-photon absorption (TPA) in a simple micro-ring resonator (MRR) configuration. While TPA is a commonly undesired phenomenon in conventional silicon devices due to its attached absorption losses and nonlinearity, we exploit it as a powerful and efficient tool for encoding spectral information, instead of using additional PDs. The input spectrum can be reconstructed from the sensed TPA current. Our proposed spectrometer achieves a bandwidth of 10 nm with a resolution of 0.4 nm while occupying a small footprint of only 16×16µm2, and the bandwidth can be further improved through several cascaded MRRs. This advancement could enable forward fully integrated and miniaturized spectrometers with low cost, which holds far-reaching applications in in situ biochemical analysis, remote sensing, and intelligent healthcare.