Polarizing mirror/absorber for visible wavelengths based on a silicon subwavelength grating: design and fabrication

Abstract

A one-dimensional 280-nm period silicon grating designed to exhibit polarization-dependent reflection or antireflection behavior at visible wavelengths has been fabricated and tested. For normally incident 575-nm light, this grating reflects less than 3% of the incident radiation polarized perpendicular to the grating grooves and approximately 23% of the orthogonal polarization. To demonstrate the grating’s broadband characteristics, reflectance measurements are presented over the free-space wavelength range 475 nm < λ₀ < 800 nm, for angles of incidence in the range 0° < θ < 40°, for polarization parallel and perpendicular to the grating grooves, and for planes of incidence parallel and perpendicular to the grooves. A description of the fabrication process is also given.