RAR Nano-Textured Diamond Pulsed LiDT Measurements

Subwavelength, low-haze, anti-reflective (AR) nano-textured surfaces are an effective replacement for thin-film AR coatings (TFARCs) with the potential to increase reliability and minimize thermo-optic effects in kW-class diamond-based laser systems. Etched directly into optical surfaces, AR nano-textured surfaces can yield high optical damage resistance combined with high transmission, low back reflection, and low absorption values equivalent to the bulk substrate material. In this initial study, Random AR (RAR) nano-structures were etched into monocrystalline chemical vapor deposited (CVD) diamond windows. Photothermal common-path interferometry (PCI) measurements at 1064nm were conducted in order to characterize the level of absorption at the surfaces and through the bulk of diamond substrates. Nano-second pulsed laser induced damage threshold (LiDT) measurements at 1064nm were conducted, and damage sites were analyzed via scanning electron microscopy (SEM) to understand damage mechanisms in both as-polished and RAR nano-textured diamond samples.