Polarization control of visible light based on composited multivariable nanowire gratings structure

The polarization regulation technology can effectively fulfill the requirements of rapid and precise identification and detection in the visible light range for polarization microscopes. The key lies in enhancing the polarization extinction ratio and achieving the optimal utilization of light. A composited multivariable nanowire gratings structure was designed based on the equivalent medium theory and the resonance enhancement mechanism of the resonator. The relationship between the structure parameters and polarization property of the structure was analyzed by numerical simulation using the finite-difference time-domain (FDTD) method, which could realize the polarization regulation function of wide angle incidence, high transmittance and high extinction ratio in the visible light band. Combined with the existing conditions of the laboratory, the nano-imprint technology was used for sample preparation and experimental verification. The experimental and simulation results show that the transmittance and extinction ratio of TM mode are higher than 60% and 35 dB respectively within the incident angle of ±35°, and the error range is about 4% at the vertical incidence of 532 nm laser source. Compared with polarizers in existing polarization microscopes, the designed structure of polarization regulation ensures high transmittance while increasing the extinction ratio by 1.5 times.