Sub-wavelength microstructures on lithium triborate surface with high transmittance and laser-induced damage threshold at 1064 nm

Abstract

This paper presents a sub-wavelength moth-eye-like antireflective structure on lithium triborate (LiB3O5, LBO) surface that can effectively promote the transmittance and maintain high laser-induced damage threshold (LIDT). Fabricated by holographic lithography and reactive ion-beam etching techniques, sub-wavelength periodic arrays can be obtained on the crystal surface. The surface morphology and transmittance were measured with atomic force microscope and spectrophotometer respectively. Single-sided transmittance of the LBO with moth-eye-like structure was confirmed to exceed 98% in the wavelength range of 1028–1300 nm, while is 98.73% at 1064 nm. For 1064 nm laser with the pulse width of 12 ns, the measured 1-on-1 LIDT is 42.57 J/cm2, which is about 2.28 times that of LBO compared with traditional antireflection (AR) coatings.