Resonant Cavity Configuration Research Articles

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.

Direct visualization of phase-matched efficient second harmonic and broadband sum frequency generation in hybrid plasmonic nanostructures

Second harmonic generation and sum frequency generation (SHG and SFG) provide effective means to realize coherent light at desired frequencies when lasing is not easily achievable. They have found applications from sensing to quantum optics and are of particular interest for integrated photonics at communication wavelengths. Decreasing the footprints of nonlinear components while maintaining their high up-conversion efficiency remains a challenge in the miniaturization of integrated photonics. Here we explore lithographically defined AlGaInP nano(micro)structures/Al2O3/Ag as a versatile platform to achieve efficient SHG/SFG in both waveguide and resonant cavity configurations in both narrow- and broadband infrared (IR) wavelength regimes (1300–1600 nm). The effective excitation of highly confined hybrid plasmonic modes at fundamental wavelengths allows efficient SHG/SFG to be achieved in a waveguide of a cross-section of 113 nm × 250 nm, with a mode area on the deep subwavelength scale (λ2/135) at fundamental wavelengths. Remarkably, we demonstrate direct visualization of SHG/SFG phase-matching evolution in the waveguides. This together with mode analysis highlights the origin of the improved SHG/SFG efficiency. We also demonstrate strongly enhanced SFG with a broadband IR source by exploiting multiple coherent SFG processes on 1 µm diameter AlGaInP disks/Al2O3/Ag with a conversion efficiency of 14.8% MW−1 which is five times the SHG value using the narrowband IR source. In both configurations, the hybrid plasmonic structures exhibit >1000 enhancement in the nonlinear conversion efficiency compared to their photonic counterparts. Our results manifest the potential of developing such nanoscale hybrid plasmonic devices for state-of-the-art on-chip nonlinear optics applications.

Exploring entanglement in open cavity parametric oscillators: From triply to doubly resonant cavities

We use a versatile model to evaluate the multipartite entanglement and the nonclassical light generation in optical parametric oscillators, exploring the differences between doubly and triply resonant cavity configurations. We demonstrate the entanglement of the pump mode with converted fields in both situations, and the fundamental differences of oscillators using parametric down conversion and four wave mixing processes as the intracavity amplification technique. The strong correlations involving the sidebands of the pump and converted fields give the signatures of a rich dynamic of multipartite entanglement.

Optical axis maladjustment sensitivity in a triangular ring resonator.

This paper estimates and measures the influences of mismatch and misalignment on continuous-wave cavity ring-down spectroscopy. We describe the theoretical differences in maladjustment effects on power transfer under different resonant cavity configurations and present a method for reducing the impact of maladjustment. Finally, we demonstrate a method for measuring the effect of maladjustment on power transfer when a Gaussian beam is matched to a triangular ring resonator.

Resonant cavity based time-domain multiplexing techniques for coherently combined fiber laser systems

This paper describes novel time-domain multiplexing techniques that use various resonant cavity configurations for increasing pulse energy extraction per each parallel amplification channel of a coherently combined array. Two different techniques are presented: a so-called N2 coherent array combining technique, applicable to a periodic pulse train, and a coherent pulse stacking amplification (CPSA) technique, applicable to a pulse burst. The first technique is a coherent combining technique, which achieves simultaneous beam combining and time-domain pulse multiplexing/down-counting using traveling-wave Fabry-Perot type resonators. The second technique is purely a time-domain pulse multiplexing technique, used with either a single amplifier or an amplifier array, which uses traveling-wave Gires-Tourmois type resonators. The importance of these techniques is that they can enable stacking of very large number of pulses, thus increasing effective amplified-pulse duration potentially by 102 to 103 times, and reducing fiber array size by the corresponding factor. This could lead to very compact coherently combined arrays even for generating very high pulse energies in the range of 1 to 100 J.

Tuning the external optical feedback-sensitivity of a passively mode-locked quantum dot laser

The external optical feedback-sensitivity of a two-section, passively mode-locked quantum dot laser operating at elevated temperature is experimentally investigated as a function of absorber bias voltage. Results show that the reverse-bias voltage on the absorber has a direct impact on the damping rate of the free-running relaxation oscillations of the optical signal output, thereby enabling interactive external control over the feedback-response of the device, even under the nearly resonant cavity configuration. The combination of high temperature operation and tunable feedback-sensitivity is highly promising from a technological standpoint, in particular, for applications requiring monolithic integration of multi-component architectures on a single chip in order to accomplish, for instance, the dual-objectives of stable pulse quality and isolation from parasitic reflections.

A 100 mW-level single-mode switchable dual-wavelength erbium-doped fiber laser

A switchable dual-wavelength CW erbium-doped fiber laser with two cascaded fiber Bragg gratings has been proposed and demonstrated experimentally at room temperature. The laser uses a linear resonant cavity configuration incorporating a Sagnac loop with a polarization controller (PC) and can switch flexibly to output a single wavelength or dual wavelengths based on the polarization hole burning (PHB) effect. The slope efficiency and maximum output power can reach 23% and 96 mW, respectively. The two lasing peaks of the laser, with a narrow linewidth output and an optical signal-to-noise ratio of more than 50 dB, are located in the C and L bands of the optical communication window, respectively. The laser shows good stability with respect to the wavelength and output power.

Compact dual-wavelength Nd:GdVO_4 laser working at 1063 and 1065 nm

We report a compact diode-laser pumped Nd:GdVO(4) laser with stable dual-wavelength output at 1063 nm and 1065 nm simultaneously. Two types of resonant cavity configurations were presented to support the stable dual-wavelength operation of the laser. Using a polarization beam splitter(PBS) included T-shaped cavity, we obtained a total power output over 5 W in two orthogonal polarized beam directions with 4 W in sigma polarization (1065.5 nm) and 1 W in pi polarization (1063.1 nm). By combining a half-wave-plate with the PBS in the laser cavity, a new configuration favoring one beam direction dual-wavelength output with same polarization direction was realized. A phenomenon of further line splitting was observed in both 1065 nm and 1063 nm.

Theory and experiments of a mode-beating noise-suppressed and mutually injection-locked Fabry-Perot laser diode and erbium-doped fiber amplifier link

By using Fabry-Perot laser diode (FPLD) as a resonant ultranarrow bandpass filter in an Erbium-doped fiber amplifier or laser (EDFA or EDFL), the theory and experiment for side-mode suppression and linewidth reduction of mutually injection-locked EDFL-FPLD and EDFA-FPLD links are demonstrated. Based on the amplified feedback injection loop, the 3-dB linewidth of 3.4 MHz for the EDFA-FPLD link is determined by using self-heterodyne interferometric spectral analysis. The EDFA-FPLD link exhibits a nearly mode-beating noise-free performance as compared to the EDFL-FPLD link. This is due to the release of the resonant cavity configuration in the EDFL-FPLD link at a cost of slightly lower side-mode suppression ratio (/spl sim/42 dB). The maximum output power of the EFDA-FPLD link is 20 mW under an FPLD input power of 0.1 mW.

Design and simulation of an uncooled double-cantilever microbolometer with the potential for ∼mK NETD

A new concept for uncooled infrared (IR) imaging with a double-cantilever microbolometer structure has been proposed. The approach has the potential of reaching a noise equivalent temperature difference (NETD) in the millikelvin range. The proposed microbolometer architecture comprises a thermally sensitive bimaterial element that controls the position of two capacitor plates coupled to the input of a low noise MOS amplifier. The top and the bottom plates of the sensing capacitor are composed of two overlapped free-standing bimaterial cantilever beams. The bimaterial element with maximum difference in thermal expansion coefficients will convert heat into mechanical movement. The orientation of the bimaterials for the top and the bottom cantilever beams is such that the metal layer on the bottom cantilever beam faces the metal layer on the top cantilever beam. IR irradiation will result in a deflection of the double-cantilever beams in opposite directions, enabling a large change in the sensing capacitor. Residual stress and curvature in each layer can be modified by an ion implantation technique. The advantages of the pixel design include extremely high sensitivity and low noise. In addition, the absorption of incident infrared irradiation can be enhanced dramatically by the aid of a resonant cavity configuration between the top and bottom plates. The design and manufacture of double-cantilever microbolometers are very flexible since the resonant cavity and the sensing capacitor gap are realized using two separate sacrificial layers. The effects of sensing capacitor gap distance, leg length, and bimaterial thickness on the microbolometer performance have also been investigated.

Magnetoelectrodynamics of a three-dimensional organic conductor: Observation of cyclotron resonance in d2

We have used an amplitude- and phase-sensitive millimeter-wave technique, in combination with a resonant cavity configuration, to observe cyclotron resonance in the three-dimensional organic conductor ${\mathit{d}}_{2}$[1,1;0]-(DMe-DCNQI${)}_{2}$Cu. The data obtained in this way are simple to analyze and serve as an extremely clear illustration of the electrodynamic response of an organic conductor in a high magnetic field. A cyclotron resonance mass of (3.35\ifmmode\pm\else\textpm\fi{}0.2)${\mathit{m}}_{\mathit{e}}$ is obtained, in agreement with the effective mass deduced from de Haas--van Alphen measurements. This result suggests that Coulomb correlations between the three-dimensional charge carriers in this material are not important and that the large effective mass is simply a result of the hybridization between a narrow Cu 3d band and the p\ensuremath{\pi} band due to the DMe-DCNQI molecules. \textcopyright{} 1996 The American Physical Society.

Demagnetization effect in strip-line cavity measurements

Stripline resonant cavities are useful for measuring the effective high-frequency permeability of small samples of high-permeability thin-film materials. However, in such an open magnetic circuit device, the effect of sample demagnetization can seriously degrade measurement accuracy unless it is recognized and corrected. Measurements with accuracy degraded by sample demagnetization are readily identified using the demagnetization effect map that is given. Approximate correction of these measurements can be accomplished by using the demagnetization correction equation and estimated demagnetization factor for the stripline resonant cavity configuration that is shown. The accuracy of this demagnetization correction is limited by the use of the approximate demagnetization factor.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Rapid Measurement of Dielectric Substrate Permittivity at X Band

A technique for rapid measurements at 8-12 GHz of dielectric substrate permittivities in the range ϵ ~9-100 is described using a novel resonant cavity configuration for inserting and removing substrate samples.

Anisotropic acoustic attenuation with new measurements for quartz at room temperatures

New measurements of the attenuation of acoustic waves in quartz have been obtained from surface excitation in a novel type of resonant cavity configuration. These are believed to be more accurate than previously published values. The attenuation is found to be proportional to the square of the frequency over the range 300 to 3000 Mc/s at a temperature of 30°C. A general theory, involving a viscosity tensor, is developed for the calculation of the attenuation of acoustic waves in crystalline solids. Symmetry of the viscosity matrix is determined by the crystal class and is the same as that of the elastic constant matrix. Numerical values for the viscosity coefficients are specific to the material and from a knowledge of these the attenuation of a given mode in a selected direction of propagation can be calculated. The validity of this analysis is confirmed by the results of the attenuation measurements in quartz and is further supported by data for silicon.