Contamination damage in pulsed 1-μm lasers

Abstract

Although thin film coating technology has evolved to the point that damage thresholds of several hundred MW/cm<SUP>2</SUP> can be routinely achieved, sealed laser systems which must be operated for extended times or at elevated temperatures frequently experience failure due to optical damage. This damage, which is frequently due to the build up of gas phase contaminants in the sealed optical compartment, occurs in spite of the fact that the lasers were designed such that the intracavity intensities are only a few tens of MW/cm<SUP>2</SUP>. Since much of our work involves designing Q-switched Nd:YAG lasers that operates over extreme environmental conditions, eliminating contamination damage at 1 micrometers is of particular interest to us. In this paper we will describe our current understanding of contamination induced damage at 1 micrometers and give an overview of the processes that can be used to eliminate such damage in fielded systems.