A micro-fiber-optic acoustic sensor based on the high-quality-factor (high-Q) resonance effect that uses a Fabry-Pérot etalon (FPE) is presented in this study. The device has been demonstrated experimentally to be a high-sensitivity acoustic sensor with a large dynamic range over a wide frequency band. Optical contact technology was used to improve the robustness of the FPE, which consists of two parallel lenses with high reflectivity exceeding 99%. An acoustic signal detection system based on phase modulation spectrum technology was also constructed. A stable and high-Q value of 106 was measured for the FPE. As a result, high sensitivity of 177.6 mV/Pa was achieved. Because of the change in the refractive index of the air when it is modulated by the acoustic waves, a frequency response of 20 Hz-70 kHz with flatness of ±2 dB was obtained and a large dynamic range of 115.3 dB was measured simultaneously. The excellent performance of the device will be beneficial for optical acoustic sensing.The avalanche is the foundation of the understanding and vast applications of the breakdown of semiconductors and insulators. Present numerical theories analyzing the avalanche photodetectors are mainly split into two categories the macroscopic empirical model with fitting parameters and the microscopic process simulation with statistical estimations. Here, we present a parameter-free analytic theory of the avalanche for a narrow-band material, HgCdTe, originated from quantum mechanics, avoiding any fitting parameter or any statistical estimation while taking advantage of both categories. Distinct from classical theory, we propose a full spatial description of an avalanche with basic concepts such as transition rate and equation of motion modified. As a stochastic process, the probability density function (PDF) of impact ionization is utilized in a generalized history-dependent theory. On account of different carrier generation character of light and leakage current, we suggest that carrier generated at different positions should be considered separately, which is done by generalized history-dependent theory in our work. Further, in our calculation, the reason for the abnormal rise of excess noise factor (ENF) observed in the experiment in single-carrier avalanche photodetectors is clarified.Photonic compressive sensing (CS) has attracted great research interest for its potentials in the acquisition of wideband sparse signals with relatively low sampling rate. The photonic CS scheme based on optical mixing using a spectral shaper can realize the mixing of a sparse signal with a high-speed pseudo-random bit sequence (PRBS), but avoids the use of high-speed electronics. In this approach, by utilizing the frequency-to-time mapping (FTTM) of chirped pulses, the spectral information on the spatial light modulator (SLM) within a spectral shaper can be projected into the time-domain waveform. However, the generated PRBS in the time domain is a unipolar sequence that alternates between 0 and 1, which leads to a nonzero-mean measurement matrix. This would result in a poorer performance of signal reconstruction compared to that with a zero-mean measurement matrix. Moreover, the length of PRBS that can be recorded in the SLM is also limited by the far-field condition. In this paper, we propose an optical mixer for photonic CS, which utilizes an SLM-based spectral shaper with complementary outputs as well as a balanced photodetector in order to generate bipolar PRBS. The performance of signal reconstruction can be significantly improved owing to the zero-mean measurement matrix induced by bipolar PRBS. In addition, the constraint on the length of PRBS can be greatly alleviated, since the obtained PRBS can still be kept zero-mean even if the PRBS is longer than that the far-field condition demands. Experimental and simulation results are presented to demonstrate the feasibility and advantage of the given approach.In three dimensional profilometry, phase retrieval technique plays a key role in signal processing stage. Fringe images need to be transformed into phase information to obtain the measurement result. In this paper, a new phase retrieval method based on deep learning technique is proposed for interferometry. Different from conventional multi-step phase shift methods, phase information can be extracted from only a single frame of an interferogram by this method. Here, the phase retrieval task is regarded as a regression problem and a hypercolumns convolutional neural network is constructed to solve it. Firstly, functions and each component of the network model are introduced in details; Then, four different mathematical functions are adopted to generate the training dataset; training and validation strategies are also designed subsequently; Finally, optimization processing is performed to eliminate local data defects in initial results with the help of polynomial fitting. In addition, hardware platform based on point diffraction interferometer is fabricated to support this method. Concluded from the experiment section, the proposed method possesses a desirable performance in terms of phase retrieval, denoising and time efficiency.The thermal gradient across a thermoelectric device is the key to convert heat energy into electricity. Here, we propose a metamaterial perfect absorber (MPA) that increases the thermal gradient across a thermoelectric device by local heat generation through absorbing thermal radiation emitted from an infinite-size blackbody radiator.  https://www.selleckchem.com/products/odq.html  The MPA, when attached on top of a bismuth telluride thermoelectric device, generates local heat that propagates to the device, resulting in an additional thermal gradient. The amount of local heat generated at the MPA and the output power of the thermoelectric device loaded with the MPA are examined through numerical calculations.Spatial zooming and magnification, which control the size of only a portion of a scene while maintaining its context, is an essential interaction technique in augmented reality (AR) systems. It has been applied in various AR applications including surgical navigation, visual search support, and human behavior control. However, spatial zooming has been implemented only on video see-through displays and not been supported by optical see-through displays. It is not trivial to achieve spatial zooming of an observed real scene using near-eye optics. This paper presents the first optical see-through spatial zooming glasses which enables interactive control of the perceived sizes of real-world appearances in a spatially varying manner. The key to our technique is the combination of periodically fast zooming eyeglasses and a synchronized high-speed projector. We stack two electrically focus-tunable lenses (ETLs) for each eyeglass and sweep their focal lengths to modulate the magnification periodically from one (unmagnified) to higher (magnified) at 60 Hz in a manner that prevents a user from perceiving the modulation.