Laser resistance dependence of interface for high-reflective coatings studied by capacitance-voltage and absorption measurement.

HfO2/SiO2 bilayer coatings and multilayer high-reflection coatings without and with a modified co-evaporated interface (MCEI) have been prepared. An MCEI is designed to be evaporated at an oxygen-deficient environment to achieve higher absorption than the conventional discrete interface. Capacitance-voltage measurements and absorption measurements demonstrate that an MCEI increases the trap density and leads to higher absorption. The laser-induced damage threshold and nano-indenter test results indicate that the MCEI multilayer coating exhibits better laser resistance and mechanical property, despite the larger absorption. The experimental results suggest that adhesive force between layers plays a more important role in nanosecond laser damage resistance than interface absorption.