Sub-Wavelength Metal-Grating Polarizer Fabricated on a Flexible Substrate

A sub-wavelength periodic grating has special characteristics that a traditional grating does not have. We, therefore, fabricated a sub-wavelength, metal, nanograting polarizer on a square of polycarbonate (PC) using nano-imprinting technology. The grating period is 278 nm, depth is 110 nm, duty cycle is 0.5, and deposited aluminum-metal layer is 70 nm thick. The performance of the sub-wavelength metal grating polarizer was tested using a spectroscopic test system. The experimental results show that when the incident wavelength is 600 nm, a double-layer flexible grating polarizer acquires good polarization characteristics. Its transmission efficiency for TM-polarized light is as high as 55%, and the extinction ratio is as high as 32 dB. The performance of the polarizer was tested using a six-channel sensor made in the laboratory. The test results show that the average error of the polarizer is 0.2002 degrees, maximum error is 1.105 degrees, and standard error is 0.7255 degrees. The manufacturing process only involves two steps: the nano-imprinting process and the metal-evaporation process; it does not involve coating, stripping, or etching an imprint adhesive. So the manufactured gratings have obvious advantages for low-cost mass production of large-area polarizers, which can be widely used in the production of semiconductor optoelectronic devices such as optical-detection devices and optoelectronic switching devices.