Increase in the optical damage threshold of a ZnSe-passivated front mirror of a laser diode

Abstract

The operation of single-mode diode lasers with a front mirror passivated by ZnSe films of different thicknesses is studied in the pulsed regime (pulse duration τ = 0.2 – 10 μs). It is found that in the case of short (0.2 μs) pulses, the catastrophic optical damage threshold grows almost linearly as the film thickness on the front mirror increases from 0.1 to 0.5 μm. It is shown that lasers with mirrors passivated by 'thick' (0.4 – 0.6 μm) ZnSe films can operate stably in the case of 'long' (2 – 10 μs) pulses. It is assumed that in this pulsed regime the ZnSe film provides an additional heat removal from the hot zone of the front mirror, and consequently increases the optical damage threshold.