Design and simulation of far infrared pixel type subwavelength double polarization grating

Polarization imaging is one of the important means of target detection and recognition, and the polarization device is the core of the system.In this paper, based on Stokes theory, a far infrared polarizing device---Two dimensional four direction array subwavelength double layer grating,is designed, which can be used for real-time measurement. Based on the equivalent medium theory, the size parameters of the micro unit are calculated.On the basis of the initial parameters, the micro cell structure is simulated and optimized.Finally, the simulation results show that the TM transmittance of the optimized double-layer grating structure is about 12% higher than that of the original one, reaching more than 90%,the extinction ratio is 25.8dB.