Manufacturing of wire grid polarizer by laser interference lithography

Wire grid polarizers (WGPs) are pivotal in the realm of polarization technology, offering superior performance in various applications. Traditional fabrication techniques, such as electron beam lithography, are often labor-intensive and expensive. Laser interference lithography (LIL) emerges as an efficient and cost-effective alternative for mass-producing high-quality gratings. The process encompasses two critical stages: pattern generation and pattern transfer. <br/> <br/> This study presents the design and experimental validation of the method for fabricating polarization gratings. Employing a helium-cadmium laser operating at 442 nm as the illumination source, coupled with a Lloyd mirror interference setup, we achieved an 800 nm period photoresist pattern. Subsequently, inductively coupled plasma etching, utilizing SF6 and O2 gases, transferred the pattern onto a silicon substrate. Double-layer aluminum gratings with an impressive maximum extinction ratio of 30 dB were created through electron beam evaporation. The methodology demonstrated exceptional reliability and stability during experimental evaluations, underscoring their potential for the future of WGP fabrication.