Sensitivity characterization of polarization operating by embedded reflective grating

In this paper, a novel embedded reflective grating (ERG) is presented to realize bi-function polarization operating at infrared band by finite element analysis (FEM). For transverse electric (TE) polarization, a two-port output (0th and −2nd orders) with an efficiency of more than 47% and excellent uniformity can be obtained. For transverse magnetic (TM) polarization, a high efficiency output of 94.72% can be achieved at the −2th order. The results of the analysis of the electric field intensity distribution, angular and wavelength bandwidths further demonstrate the advantages of the proposed grating. In addition, the tolerance analysis of period and duty cycle prove the feasibility of the grating in practical production.

Design of Power Splitters Based on Hybrid Plasmonic Waveguides

Plasmonic power splitters based on hybrid plasmonic waveguides (HPWs) are proposed and investigated. The HPW consists of a high-permittivity semiconductor nanowire embedded in a SiO2 dielectric film near a metal surface. The propagation behaviors of Surface Plasmon Polaritons (SPPs) in HPWs are numerically simulated by the 3D finite-difference time-domain (FDTD) method. The incident field is transferred from the middle waveguide to the waveguides on both sides due to the coupling between adjacent waveguides. The intensity distributions can be explained by the multimode interference of SPPs supermodes. According to the field intensity distribution of five HPWs, we design a 1 × 3 power splitter and a 1 × 2 power splitter by reducing the length of some specific waveguides.

Numerical study on key parameters of a Magnetorheological Fluid reciprocating seal with increasing width of pole teeth and pole piece

In order to solve the problem of reciprocating seal for hydraulic cylinder, a new structure of Magnetorheological fluid (MRF) reciprocating seal with increasing width of pole teeth and pole piece was designed. The theoretical analysis of MRF reciprocating seal is carried out. The magnetic field intensity distribution in the sealing gap of MRF reciprocating seal was analyzed by finite element method. According to the pressure capability formula of MRF, the theoretical pressure capability is calculated. The influences of structure parameters such as the number of magnetic sources, sealing gap height, pole teeth length, the ratio of permanent magnet height to its length, the ratio of pole piece height to shaft radius on the sealing capabilities were studied. The results showed that the pressure capability of MRF reciprocating seal increases with the increase of the number of magnetic sources and with the decrease of the sealing gap height. With the increase of the pole tooth length, the pressure capability of the reciprocating seal increases. With the increase of the ratio of permanent magnet height to its length, the pressure capability of the reciprocating seal increases first and then decreases. With the increase of the ratio of the pole piece height to shaft radius, the pressure capability of the MRF reciprocating seal increases first and then decreases.

A Fast Calculation Method of Far-Field Intensity Distribution with Point Spread Function Convolution for High Energy Laser Propagation

The turbulence effect, thermal blooming effect, laser beam aberration, platform jitter, and other effects in the process of high energy laser propagation in the atmosphere will cause serious degradation of laser beam quality, which will have a negative impact on the actual application of laser propagation engineering. It is important in the engineering application of high-energy laser propagation to evaluate the far-field intensity distribution quickly. Based on the optical transfer function (OTF) theory of imaging system, the propagation process of high-energy lasers is modeled as the imaging process of point source. By using the convolution of point spread function (PSF) of jitter, turbulence, thermal blooming, and aberration of emission system, fast calculation of the far-field intensity distribution of high energy laser is realized. The calculation results are compared with those obtained by the 4D wave optics simulation program in different propagation scenarios. The results show that the calculated facula distribution and encircled energy of this method are in good agreement with the simulation results of wave optics, which can realize the fast and accurate evaluation of the far-field intensity distribution of high-energy laser propagation and provide a reference for practical engineering application.

A Single Far-Field Deep Learning Adaptive Optics System Based on Four-Quadrant Discrete Phase Modulation

In adaptive optics (AO), multiple different incident wavefronts correspond to a same far-field intensity distribution, which leads to a many-to-one mapping. To solve this problem, a single far-field deep learning adaptive optics system based on four-quadrant discrete phase modulation (FQDPM) is proposed. Our method performs FQDPM on an incident wavefront to overcome this many-to-one mapping, then convolutional neural network (CNN) is used to directly predict the wavefront. Numerical simulations indicate that the proposed method can achieve precise high-speed wavefront correction with a single far-field intensity distribution: it takes nearly 0.6ms to complete wavefront correction while the mean root mean square (RMS) of residual wavefronts is 6.3% of that of incident wavefronts, and the Strehl ratio of the far-field intensity distribution increases by 5.7 times after correction. In addition, the experiment results show that mean RMS of residual wavefronts is 6.5% of that of incident wavefronts and it takes nearly 0.5 ms to finish wavefront reconstruction, which verifies the correctness of our proposed method.