Laser testing of anti-reflection micro-structures fabricated in ZnSe and chromium-ion doped ZnSe laser gain media

Academic Article

Abstract

  • An expanded study has been completed of the pulsed and continuous wave (CW) laser induced damage threshold (LiDT) of surface relief anti-reflection (AR) microstructures (ARMs) etched in zinc selenide (ZnSe) crystals and chromium-ion-doped (Cr:ZnSe) laser gain media. In multiple-sample per variant testing at wavelengths of 2095 and 2940nm, the pulsed laser damage resistance of ARMs textured ZnSe crystals was found to be equivalent to untreated, as-polished crystals, with an LiDT as much as 5 times that of thin-film AR coated ZnSe crystals. Similar results were found for Cr:ZnSe crystals tested at 2940nm, but mixed results were found for pulse testing at 2095nm. In accumulated power CW damage testing at a wavelength of 1908nm, neither untreated nor ARMs treated ZnSe crystals could be damaged after long duration exposures at a maximum system intensity of 28.6 MW/cm2, a value many times higher than typically found with thin-film AR coated ZnSe. For Cr:ZnSe gain media, the CW LiDT was observed to be dependent on the focused beam size at the sample surface, with thresholds for untreated and ARMs-treated Cr:ZnSe being nearly equivalent, ranging from 0.6 MW/cm2 for the largest spot size, to 2.1 MW/cm2 for a spot area 4 times smaller. An operational laser test was performed where an ARMs textured Cr:ZnSe crystal operated with higher slope efficiency and 1.5 times the output of a thin-film AR coated crystal in an identical resonator configuration.
  • Authors

    Published In

    Digital Object Identifier (doi)

    Author List

  • Hobbs D; Macleod B; Sabatino E; Mirov S; Martyshkin D; Mirov M; Tsoi G; Mcdaniel S; Cook G
  • Start Page

  • 3377
  • End Page

  • 3388
  • Volume

  • 7
  • Issue

  • 9