Fabrication of 150 nm period grating in fused silica by two-beam interferometric laser induced backside wet etching method

Abstract

Fused silica gratings with periods of 154 nm, 266 nm, and 550 nm have been fabricated by the method of two-beam interferometric laser induced backside wet etching (TWIN-LIBWE). The spatially filtered pulses at 266nm were splitted into two parts and interfered at an incident angle of 60(o), 30(o), and 14(o), respectively, on the backside surface of a fused silica plate contacting with the liquid absorber. The morphology of the etched gratings was characterized by atomic force microscope. According to our knowledge, the produced 154 nm period is the smallest grating constant generated by laser techniques directly in fused silica at present.