The Effect of Moisture and Temperature on Optical Coatings Used in Eye-safer Lasers

Abstract

Erbium (Er):yttrium aluminum garnet (YAG) lasers are currently under development at the U.S. Army Research Laboratory (ARL) as eye-safer alternatives to neodymium (Nd):YAG for countering rockets, artillery, and mortar (CRAM). Anomalous increases in laser output have been observed during the 30-60 min period after turn-on. A hypothesis was that one or more of the three optical coatings (anti-reflection, dichroic, and partially reflecting) in the laser cavity were absorbing or desorbing moisture. On the basis of the baking-out measurements described here, we attribute the increase in laser power to moisture being driven out of the dichroic coating, increasing its reflectivity at the laser wavelength. We have also measured the effect of operating temperature on a dichroic coating that has already been baked-out.

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Document Details

Document Type
Technical Report
Publication Date
Sep 01, 2010
Accession Number
ADA620102

Entities

People

  • Aaron Z. Chan
  • Carl E. Mungan
  • Jeffrey O. White

Organizations

  • United States Army Research Laboratory

Tags

Communities of Interest

  • Weapons Technologies

DTIC Thesaurus Topics

  • Aluminum
  • Antireflection Coatings
  • Artillery
  • Coatings
  • Elements
  • Garnet
  • Laser Resonators
  • Lasers
  • Materials
  • Materials Laboratories
  • Metals
  • Military Research
  • Moisture
  • Optical Coatings
  • Reflection
  • Refractive Index
  • Yttrium Aluminum Garnet

Fields of Study

  • Physics

Readers

  • Optical Physics and Photonics.
  • ballistics.

Technology Areas

  • Directed Energy