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Increasing the laser-induced damage threshold of single-crystal ZnGeP{sub 2}

Journal Article · · Journal of the Optical Society of America. Part B, Optical Physics
; ; ;  [1]
  1. BAE Systems, Advanced Systems and Technology, P.O. Box 868, MER15-1813, Nashua, New Hampshire 03061-0868 (United States)
The laser-induced damage threshold (LIDT) of single-crystal zinc germanium phosphide (ZGP), ZnGeP{sub 2}, was increased to 2 J/cm{sup 2} at 2.05 {mu}m and a 10 kHz pulse rate frequency (double the previously measured value of 1 J/cm{sup 2}). This increased LIDT was achieved by improving the polishing of ZGP optical parametric oscillator crystals. Two different polishing techniques were evaluated. Surfaces were characterized using scanning white-light interferometry to determine rms surface roughness and sample flatness. The photon backscatter technique was used to determine the degree of surface and subsurface damage in the sample induced through the fabrication process. The effect of subsurface damage in the samples was studied by removing different amounts of material during polishing for otherwise identical samples. Statistical LIDT was measured using a high-average-power, repetitively Q-switched Tm,Ho:YLF 2.05 {mu}m pump laser. On average, lower surface roughness and photon backscatter measurements were a good indicator of ZGP samples exhibiting higher LIDT. The removal of more material during polishing significantly improved the LIDT of otherwise identical samples, indicating the importance of subsurface damage defects in the LIDT of ZGP.
OSTI ID:
20861065
Journal Information:
Journal of the Optical Society of America. Part B, Optical Physics, Journal Name: Journal of the Optical Society of America. Part B, Optical Physics Journal Issue: 11 Vol. 23; ISSN JOBPDE; ISSN 0740-3224
Country of Publication:
United States
Language:
English