In this work we are analyzing a way to use argon plasma etching method in order to make the prototype of high LIDT (Laser Induced Damage Threshold) fixed beam expander suitable for UV laser micromachining systems. We tested 5 most popular fused silicas (FS) in photonics market - Corning 7980 0F, Corning 8655 0F, Suprasil 300, Suprasil 1 and JGS1. Different thickness (from 0 nm to 150 nm) of commercially polished various fused silica glasses were removed and optical-physical properties were investigated. Each substrate was tested in the LIDT measuring setup. Experimental results showed that optimal etching depth for various fused silica substrates is - 100 ± 7 nm. LIDT (1000-on-1 at 355 nm) of developed beam expander with etched substrates was 17.7±2.9 J/cm2. In comparison, LIDT of beam expander with non-etched FS substrates has only 4.9 ± 1.7 J/cm2.
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