Light transmittance and extinction ratio are the two most important properties to characterize the performance of grating-based polarizers. Basic research was conducted to study the structural effect of grating line cross section on the polarization characteristics. To maximize both the transmittance and the extinction ratio, the grating materials, the geometrical dimensions and the grating line structure are systematically studied. Then, a shape in the form of a rectangle stacked with a parabolic shape on top was proposed for achieving both high transmittance and extinction ratio. Nanofabrication for subwavelength gratings in Al was carried out. High transmittance over 70% was achieved, but the extinction ratio was still not satisfactory, which was ascribed to the thickness in the fabricated grating not being large enough. However, the measured ratio fits to the simulation result well, indicating that the designed grating parameters can be a good basis for high-quality polarizers based on subwavelength gratings of aluminum.
展开▼
