High-power KrF laser transmission through optical fibers and its application to the triggering of gas switches

Abstract

The fundamental transmission characteristics of KrF laser radiation (248 nm) through the step-index-type fused quartz fiber have been determined. For the step-index-type fused quartz fiber used the transmission loss is about 0.5 dB/m at power densities up to 3.9 MW/cm2 and 2 dB/m at 100 MW/cm2. One of the applications of this intense UV KrF laser transmission via optical fibers is the development of a gas insulated spark-gap switch trigger by a KrF laser through a 2-m-long optical fiber. As a result, at a voltage 90% of the self-breakdown voltage and at an illumination power density of 1.2 MW/cm2, a full trigger jitter of less than 5 ns is realized and it corresponds to a 1-σ jitter of less than 1 ns. The illumination energy is as low as 10 μJ/shot.