Simulation Study of Near-Infrared Polarizing Filter Based on Plas-mon Effect

Based on the theory of Surface Plasmons (SPs), this paper combines the Finite Difference Time Domain method (FDTD) to simulate the polarization characteristics of periodic sub-wavelength metal gratings, and uses the equivalent medium theory. Explain the reasons for the polarization of the sub-wavelength grating, and analyze in depth the influence of the period, duty cycle, thickness and metal materials of the sub-wavelength metal grating on the polarization characteristics of the transmitted light within the incident wavelength of 0.8~1.7 μm. The results show that the com-monality of Al and Au is that both can control the polarization of the metal grating. The difference is that Al controls the extinction ratio more obviously, and Au controls the transmittance more obviously. In addition, the period of the sub-wavelength metal grating is directly proportional to the transmittance and extinction ratio; the duty cycle is directly proportional to the transmittance and inversely proportional to the extinction ratio; the thickness of the grating has a more obvious influence on the extinction ratio. This research lays the foundation for the application of the near-infrared polarization filter film, the core component of the polarization spectrum imaging chip.