Guyfinley8856

This paper presents a detailed analysis examining the absorption performance of a metal-dielectric slab with subwavelength size periodic perforations exploiting quarter-wave impedance matching (QWIM) technique within long wave infrared (LWIR) regime (8-12µm). Integration of perforations to a simple stack with various period sizes and perforated area ratios are examined through theory, simulation, and measurements that are in great agreement. Advantages of perforated absorbers for thermal detectors are discussed in maximizing optical absorption and reducing thermal-mass point of view. Introducing perforation in umbrella type absorbers is mainly employed for reducing the thermal-mass while maintaining the high absorption performance. Within the scope, it is experimentally shown that a perforation ratio (width/period) of 50% with square holes for the umbrella layer is possible without degrading the maximum LWIR absorption performance of 96% when the sheet resistance of Rs=400Ω/□ is employed for the absorbing metal layer, which is close to free space impedance of 377Ω/□. Nevertheless, this ratio can be increased up to 77% by depositing a thicker absorber metal with smaller sheet resistance, such as Rs=100Ω/□ while still maintaining an average absorption performance of 93%, which are all predicted numerically by simulations and physically explained through effective medium approach (EMA).A stable frequency downlink transmission scheme, which delivers the frequency signal back to the central station from an arbitrary injection point along a radio-over-fiber (RoF) loop link, is proposed and demonstrated. The frequency signal at the arbitrary remote point is injected into the RoF loop link in both clockwise and counter-clockwise directions, simultaneously. The phase variation induced by the fiber loop link is obtained in real time with the help of a round-trip assistant frequency signal. The phase error can be exactly cancelled by a series of frequency mixing (i.e., up-conversion and down-conversion) among the signals. In the experiment, a 1.21-GHz frequency signal at an arbitrary remote point is downlink transferred to the central station in a 45-km fiber loop link. The result shows the overlapping Allan deviation (ADEV) of 1.04×10-12 at 0.1 s, 1.3×10-13 at 1 s and 1.1×10-15 at 104 s, respectively. The phase error correction operates entirely at the central station, leaving a simple and robust configuration of the remote site. No active adjusting part is integrated, and the all-passive compensation achieves an endless phase error correction range, as well as quick response to fiber delay changes.We demonstrated stochastic switching in a bistable system implemented with the Rydberg atomic ensemble, which is realized by cascaded Rydberg excitation in a cesium vapor cell. Measurement of Rydberg state's population by means of the electromagnetically induced transparency allows us to investigate the nonlinear behavior in Rydberg atomic ensemble experimentally. The transition between the two states of the bistable system is driven by the intensity noise of the laser beams. Rydberg atomic ensemble accumulates energy in an equilibrium situation and brings the nonlinear system across the threshold, where stochastic switching occurs between the two states.We explore the tilted-pulse-front excitation technique to control the superradiant emission of terahertz (THz) pulses from large-area photonconductive semiconductor switches. Two cases are studied. First, a photoconductive antenna emitting into free space, where the propagation direction of the optically generated THz beam is controlled by the choice of the tilt angle of the pump pulse front. Second, a THz waveguide structure with an integrated photoconductive window for the generation of THz radiation, where the injection of the THz radiation into a waveguide mode is optimized by the pulse front tilt. By providing long interaction lengths, such a waveguide-based optical-pump/THz-probe set-up may provide a new platform for the study of diverse short-lived optically induced excitations.Recently, the miniature spectrometer based on the optical filter array has received much attention due to its versatility. Selleckchem TMP195 Among many open challenges, designing efficient and stable algorithms to recover the input spectrum from the raw measurements is the key to success. Of many existing spectrum reconstruction algorithms, regularization-based algorithms have emerged as practical approaches to the spectrum reconstruction problem, but the reconstruction is still challenging due to ill-posedness of the problem. To alleviate this issue, we propose a novel reconstruction method based on a solver-informed neural network (NN). This approach consists of two components (1) an existing spectrum reconstruction solver to extract the spectral feature from the raw measurements (2) a multilayer perceptron to build a map from the input feature to the spectrum. We investigate the reconstruction performance of the proposed method on a synthetic dataset and a real dataset collected by the colloidal quantum dot (CQD) spectrometer. The results demonstrate the reconstruction accuracy and robustness of the solver-informed NN. In conclusion, the proposed reconstruction method shows excellent potential for spectral recovery of filter-based miniature spectrometers.We present a compact on-chip resonator enhanced silicon metal-semiconductor-metal (MSM) photodetector in 850 nm wavelength band for communication and lab-on-chip bio-sensing applications. We report the highest responsivity of 0.81 A/W for a 5 µm long device. High responsivity is achieved by integrating the detector in a silicon nitride ring resonator. The resonance offers 100X responsivity improvement over a single-pass photodetector due to cavity enhancement. We also present a detailed study of the high-speed response of the cavity and single-pass detector. We report an electro-optic bandwidth of 7.5 GHz measured using a femtosecond optical excitation. To the best of our knowledge, we report for the first time silicon nitride resonator integrated Si-MSM detector in SiN-SOI platform.Light field cameras have been employed in myriad applications thanks to their 3D imaging capability. By placing a microlens array in front of a conventional camera, one can measure both the spatial and angular information of incoming light rays and reconstruct a depth map. The unique optical architecture of light field cameras poses new challenges on controlling aberrations and vignetting in lens design process. The results of our study show that field curvature can be numerically corrected for by digital refocusing, and vignetting must be minimized because it reduces the depth reconstruction accuracy. To address this unmet need, we herein present an optical design pipeline for light field cameras and demonstrated its implementation in a light field endoscope.Replacing part of a conventional optical circuit with a topological photonic system allows for various controls of optical vortices in the optical circuit. As an underlying technology for this, in this study, we have realized a topological converter that provides high coupling efficiency between a normal silicon wire waveguide and a topological edge waveguide. After expanding the waveguide width while maintaining single-mode transmission from the Si wire waveguide, the waveguides are gradually narrowed from both sides by using a structure in which nanoholes with C6 symmetry are arranged in a honeycomb lattice. On the basis of the analysis using the three-dimensional finite-difference time-domain method, we actually fabricated a device in which a Si wire waveguide and a topological edge waveguide were connected via the proposed topological converter and evaluated its transmission characteristics. The resulting coupling efficiency between the Si wire waveguide and the topological edge waveguide through the converter was -4.49 dB/taper, and the coupling efficiency was improved by 5.12 dB/taper compared to the case where the Si wire waveguide and the topological edge waveguide were connected directly.This is a Reply to the Comment by Meiler, Frank, and Giessen directed to a recent paper "Dynamic tailoring of an optical skyrmion lattice in surface plasmon polaritons" [Opt. Express28, 10320 (2020)10.1364/OE.384718] regarding to the existence of Bloch-type skyrmions in the magnetic field of surface plasmon polaritons.We comment on a recent paper entitled "Dynamic tailoring of an optical skyrmion lattice in surface plasmon polaritons" [Opt. Express28, 10322 (2020)10.1364/OE.384718] and disprove the assertion that Bloch-type skyrmions exist in the magnetic field of surface plasmon polaritons.The figure-9 fiber laser exhibits excellent performance, but improvement of its output pulse energy is restricted by the laser structure design that ensures self-starting mode-locking. In this paper, we propose and verify a novel method to increase the pulse energy of the self-starting figure-9 fiber laser. By reducing the linear phase shift step-by-step in a self-starting figure-9 laser and synchronously increasing the pump power, the output pulse energy can be increased while the laser can always operate in the single-pulse mode-locking region. Using a 112-MHz dispersion-managed soliton figure-9 fiber laser, the effectiveness of our proposed method is verified, and the laser output pulse energy has been successfully increased to 1.4 nJ, which is 5.6 times the pulse energy before the boost. The entire self-starting mode-locking of the laser including the program-controlled joint adjustment is less than 1s with 100% success rate of more than 100 tests. This method can in principle solve the limitation on the output pulse energy caused by the self-start of the figure-9 laser.The majority of 2D IR spectrometers operate at 1-10 kHz using TiSapphire laser technology. We report a 2D IR spectrometer designed around YbKGW laser technology that operates shot-to-shot at 100 kHz. It includes a home-built OPA, a mid-IR pulse shaper, and custom-designed electronics with optional on-chip processing. We report a direct comparison between YbKGW and TiSapphire based 2D IR spectrometers. Even though the mid-IR pulse energy is much lower for the YbKGW driven system, there is an 8x improvement in signal-to-noise over the 1 kHz TiSapphire driven spectrometer to which it is compared. Experimental data is shown for sub-millimolar concentrations of amides. Advantages and disadvantages of the design are discussed, including thermal background that arises at high repetition rates. This fundamental spectrometer design takes advantage of newly available Yb laser technology in a new way, providing a straightforward means of enhancing sensitivity.In this study, we present first-time fabrication of FBGs in all ZEONEX-based SMPOFs with a single 25 ns pulse of 248 nm UV irradiation over a 12-month period, which opens up new frontiers in optics and photonics for the effective fabrication of polymer optical fiber Bragg gratings (POFBGs), permitting mass producibility of them. POFBGs were characterized by subjecting them to various physical parameters including temperature and tensile strain. Strain responses of FBGs with similar grating strengths fabricated with 248 nm and 325 nm He-Cd laser irradiations were explored over a year to demonstrate their long-term stability and applicability. Owing to the unique features of the proposed sensing device fabricated by embedding POFBGs in silicone rubber, a good performance in the detection of human heart rate with an amplitude of 4 pm, which is 4 times higher compared to that of silica single mode fiber (SMF) was demonstrated. The response of the sensing device during a human respiration process was also explored where exhalation and inhalation were monitored and distinguished while the breath was held.