Enhanced laser-induced damage performance of all-glass metasurfaces for energetic pulsed laser applications

To fabricate optical components with surface layers compatible with high-power laser applications that may operate as antireflective coatings, polarization rotators, or harness physical anisotropy for other uses, metasurfaces are becoming an appealing candidate. In this study, large-beam (1.05 cm diameter) 351-nm laser-induced damage testing was performed on an all-glass metasurface structure composed of cone-like features with a subwavelength spacing of adjacent features. These structures were fabricated on untreated fused silica glass and damage tested, as were structures that were fabricated on fused silica glass that experienced a preliminary etching process to remove the surface Beilby layer that is characteristic of polished fused silica. The laser-induced damage onset for structures on untreated fused silica glass was 19.3J⋅c m ^-2, while the sample that saw an initial pretreatment etch exhibited an improved damage onset of 20.4J⋅c m ^-2, only 6% short of the reference pretreated glass damage onset of 21.7J⋅c m ^-2. For perspective, the National Ignition Facility operational average fluence at this wavelength and pulse length is about 10J/c m ². At a fluence of 25.5J⋅c m ^-2, the reference (pretreated) fused silica initiated 5.2 damage sites per m m ², while the antireflective metasurface sample with a preliminary etching process treatment initiated 9.8 damage sites per m m ². These findings demonstrate that substrate-engraved metasurfaces are compatible with high energy and power laser applications, further broadening their application space.