Near-infrared bilayer nanowire grid polarizer array fabricated using soft nanoimprint lithography

We fabricated a cost-effective and tractable near-infrared nanowire grid polarizer array with six different directional grating elements on a Borofloat 33 glass substrate at once using a soft nanoimprint and metal thermal evaporation process. Each element consists of a 200-nm period bilayer Al grating with an area of 1.3 × 1.3 mm2. Scanning electron microscopy images reveal that each unit of the polarizer array has an intact nanostructure without large-area damage. Meanwhile, the TM transmittance of each element exceeds 65% in the wavelength range of 1 to 2.5 μm, and of particular note, it is >70 % in the wavelength range of 1.2 to 2.5 μm. The extinction ratio is more than 20 dB in 1.38- to 2.5-μm wavelength range, proving that the polarizer array has good polarization characteristics. Such a polarizer array has low costs and better compatibility with microfabrication processes, which can be used as an element of near-infrared polarization image detection equipment.