Dimitrov, NikolayZhekova, MayaZhang, YinyuPaulus, Gerhard G....
6页
查看更多>>摘要：Among the existing techniques for measuring ultrashort pulse durations, the two classical second-order methods - interferometric and the background-free autocorrelation - are distinguished due to their simplicity and reliability. In this work we report on a technique that allows realignment-free switching between these two modes of autocorrelation. It is based on a collinearly aligned inverted-field interferometer and an optical vortex plate that is added/removed in front of the device in order to switch between both modes. Experiment and theoretical modeling confirm the effectiveness of the technique down to the 10-fs range.
查看更多>>摘要：In the process of multiple-image encryption, there are some problems such as low reconstruction accuracy, easy cross-talk, and poor robust performance. To solve these problems, a multiple-image encryption algorithm based on Radon transform and ghost imaging is proposed. Radon transform is applied to the encryption system of ghost imaging. The Cartesian coordinates of the two-dimensional images are firstly converted to the polar coordinates. Then, the Radon transform is fully used to obtain the projection of digital images at arbitrarily given angles. By adjusting the projecting angle interval, the spatial division multiplexing is used to realize the multiple-image encryption. By the numerical simulations and optical experiments, the feasibility of the proposed encryption system is verified. The results show that the proposed system not only reduces the amount of data transmission, but also improves the precision of the reconstructed image and the robustness of the encryption system.
查看更多>>摘要：An optical absorber with Fano response is interesting for refractive index sensing based on the Plasmonic thin-film Metal-insulator-metal (MIM) structure. In this paper, a symmetrical structure with a self-similar formation to obtain a Fano response is designed. The symmetrical form of the absorber makes independent of incident wave polarization. The coupling between the central and parasitic elements provides the Fano response, and the simulations support this characteristic. This coupling converts two bright modes for each basic structure to bright and dark modes in the final structure. This structure is modified for 927 and 1127 nm, and the parametric studies are used to improve absorption up to 99% in both peaks by reducing the reflection to improve the figure of merit (FOM) of the sensor. The maximum sensitivity and FOM are obtained 285 RIU/nm and 1046 RIU-1, respectively. In addition, the circuit model analysis is used to describe the elements effect in the proposed absorber.
查看更多>>摘要：A perovskite solar cell with FTO/CuSCN/Perovskite/TiO2/Metal was proposed and analyzed theoretically using SCAPS-1D software. The electron transport layer (ETL), Absorber layer and hole transport layer (HTL) were optimized by varying their thickness, doping concentration and defect density. The absorber thickness and doping seem to heavily influence the performance of the device. ETL optimization also provided a significant boost in the efficiency of the device. This thickness of 900 nm and a light doping of 1014 cm(-3) in absorber layer along with 1017 cm(-3) donor density of ETL provided the highest efficiency of 28.9%. After proper optimization the perovskite solar cell has a power conversion efficiency of 28.9% with 82.08% fill factor. The open circuit voltage is 1.1 V and the short circuit current is 31.192 mA/cm(2).
查看更多>>摘要：The strong need in life science and medicine research has prompted the development of wide-field, high resolution and real-time microscopic imaging based on camera array. For large-scale sub-image stitching on the order of billion pixels, it is highly challenging to calibrate the camera array with low-overlapping fields of view (FOVs). To address the challenge, we propose a camera array calibration method to obtain the complete camera model and global mapping coordinates. The method utilizes spatiotemporal structured light encoding provided by a spatial light modulator to establish the correspondence between the physical coordinates of the keypoints in the object plane and their pixel coordinates in the sub-image plane. This achieves fast and accurate calibration of a camera-array-based microscopic system without the requirement of sub-FOV overlap. A series of experiments, including reprojection evaluation and global image stitching on the resolution chart and biological specimen slice, verified the effectiveness of the proposed approach. The method supports calibration of global geometric position with 0.2-pixel accuracy and has a broad potential for application to general camera array-based imaging systems.
查看更多>>摘要：Due to a high Verdet constant and paramagnetic properties, the ceramics based on terbium oxide is a promising candidate as a magneto-optical medium for developing cryogenic Faraday isolators. Cryogenic cooling suppresses thermal effects and leads to an increase in the maximum power of the laser radiation passing through the Faraday isolator at the same isolation ratio. We have measured the thermally-induced depolarization and the thermal lens within the 81-297 K temperature range and the linear absorption coefficient alpha(0) within the 83-297 K temperature range in (Tb0.9Y0.1)(2)O-3. The ratio of the effective thermooptical constants P-eff/Q(eff) was similar to 6.44 in the studied temperature region. On cooling to LN2 temperature, the parameters alpha(0)Q(eff)/kappa and alpha P-0(eff)/kappa (kappa is the thermal conductivity coefficient) decreased by a factor of similar to 5.2. The alpha(0) was temperature independent. The results of the study demonstrate great prospects for the use of terbium oxide based ceramics in cryogenic Faraday isolators.
NSTL
Elsevier