The Design of the Sub-Wavelength Wire-Grid Polarizer

According to the request of the sensitive wave band of 0.38 mu m-0.52 mu m of the bionic micro-nano navigation sensor, the paper designed a wire-grid polarizer which can be effectively used in the region of blue-violet light spectrum based on rigorous coupled-wave theory. The difference between the designed wire-grid polarizer and the conventional wire-grid polarizer is that the former adds the magnesium fluoride film between the substrate and the wire-grid, and etches a portion of the magnesium fluoride Mm. Numerical results and theoretical analysis presented that the designed wire-grid polarizer is a broadband, high TM polarization transmission efficiencies and high extinction ratios polarizer. The paper also discussed the performance of the designed grating affected by oxidation of aluminum. The effects of the oxide layer are that the TM transmission efficiencies increase slightly, whereas the extinction ratios decrease rapidly. The paper had the conclusion that the effects of the oxide layer can be almost attributed to the reduction in duty cycle and wire thickness it causes. Finally, the paper discussed the relationship between the number of orders retained and the convergence of the calculation numerical. Numerical results and theoretical analysis presented that the rate of convergence of the TM diffraction efficiency is much slower than the rate of convergence of the TE diffraction efficiency. The paper concluded that the reason of the phenomenon is that the TM polarization has multiple vector components which lead to large evanescent field.