High-efficiency fused-silica reflection grism

A fused-silica reflection grism (combination of grating and prism) based on the phenomenon of total internal reflection (TIR), and used in the -1st order, is designed and fabricated. The grism is etched directly into the fused-silica prism, which greatly facilitates the use of the TIR grating as no other angle coupling devices are involved. The grating profile is optimized by the use of the rigorous coupled-wave analysis method. Diffraction efficiency of larger than 99% at a wavelength of 980 nm for TM-polarized waves can be theoretically obtained. Two-beam interference lithography and inductively coupled plasma etching techniques are used to manufacture such grism. Diffraction efficiencies of larger than 95% are experimentally demonstrated. (C) 2014 Optical Society of America