Measurement of multiphoton absorption and electron avalanche in optical thin films

Abstract

Measurements on nonlinear processes caused by multiphoton absorption and electron avalanche in optical thin films have been carried out using KrF lasers of 20-ns and 1.7-ps pulse duration. Multiphoton absorption of the order of 10~7 J was detected by a photoacoustic signal, and the nonlinear growth of photo-induced current due to the electron avalanche was analyzed dynamically. The correlation between damage threshold and carrier lifetime was investigated for oxide and fluoride coatings.