Periodic sub-wavelength structures with large phase retardation fabricated by glass nanoimprint

Abstract

One-dimensional periodic sub-wavelength structures (SWSs) with a period of 300 nm were fabricated on a bismuth germano-borate glass plate by a direct glass nanoimprint method using SiC molds. The borate glass had a refractive index of 1.82 at 587.6 nm wavelength, an internal transmittance higher than 80% at a thickness of 3 mm in the visible wavelength region, and a deformation temperature of 468°C. SWSs with height of a few hundred nanometers were simultaneously fabricated on both surfaces of the glass plate by the glass nanoimprint at 488°C for 120 s with 8 MPa in pressure. The SWSs showed form birefringence. A phase retardation of 0.23 λ was observed between transverse electric (TE)- and transverse magnetic (TM)-polarized beams at 400 nm wavelength.