Fabrication of Phase Mask for Optical Fiber Grating
A fused silica phase mask with the period of 1069nm, and ruled area 50×50mm2 has been fabricated by a new technique, which combines holographic-ion beam etching and reactive ion beam etching. This involves several steps: coating of substrates with controlled thickness of photoresist, formation of a grating mask by holograph interference exposure and development, and finally transferring etching of this mask into the fused silica substrate to form a permanent phase mask. Experimental measurements have shown that the zero order diffraction efficiency is less than 4% and the plus and minus first-order diffraction efficiency is more than 35%. Theoretical analysis has shown that these phase masks can be used for fabricating UV written Fiber Bragg Gratings.
Guo Fan JIN, Wing Bun LEE, Chi Fai CHEUNG and Suet TO
Q. Liu et al., "Fabrication of Phase Mask for Optical Fiber Grating", Key Engineering Materials, Vols. 364-366, pp. 719-723, 2008