Employing SiO₂ buffer layer to improve adhesion of the frequency-doubled antireflection coating on LBO

Abstract

Frequency-doubled antireflection coatings simultaneously effective at 1064 nm and 532 nm were deposited on the lithium triborate (LiB₃O₅ or LBO) crystals using the electron beam evaporation method. Comparing with the sample without buffer layer, it is found that the adhesion of the sample with buffer layer of SiO₂ between coating and LBO substrate is improved significantly from 137.4 mN to greater than 200 mN. And the laser-induced damage threshold is increased by 20% from 15.1 J/cm² to 18.6 J/cm². The strengthening mechanism of adhesion of the buffer layer of SiO₂ is discussed by considering full plastic indentation and shear theory.

Keywords

frequency-doubled antireflection coating / LBO crystal / adhesion

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