Interaction of high-power infrared radiation with germanium

D. Seo, L. C. Feldman, N. H. Tolk, P. I. Cohen

Research output: Contribution to journalConference articlepeer-review

3 Scopus citations

Abstract

We have observed and characterized wavelength-dependent laser damage thresholds in crystalline germanium induced by trains of high-power infrared picosecond laser pulses at wavelengths ranging from 2.8 μm to 5.2 μm, using the Vanderbilt Free-Electron Laser. In this wavelength range, photon energies are well below the band-gap energy. As the wavelength is increased, threshold fluences are observed to increase by a factor of five over the studied wavelength range. Two- and three-photon absorption is the predominant photon energy absorption mechanism up to 4.4 μm. At wavelengths above 4.8 μm tunnel absorption appears to be the primary absorption mechanism. Wavelength and fluence dependent transmission and reflection measurements provide valuable insight into the nature of the damage mechanisms.

Original languageEnglish (US)
Number of pages1
JournalProceedings of SPIE - The International Society for Optical Engineering
Volume7132
DOIs
StatePublished - Dec 1 2008
Event40th Annual Boulder Damage Symposium - Laser-Induced Damage in Optical Materials: 2008 - Boulder, CO, United States
Duration: Sep 22 2008Sep 24 2008

Keywords

  • Free-electron laser
  • Germanium
  • Laser induced damage
  • Mid-infrared
  • Transmittance

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