Infrared absorption signature on laser-damaged optical thin films

摘要

Optical coating degradation under laser irradiation can take several forms. Perhaps the most common thatnis not due to particulates is thermal breakdown, caused by heating of the coating to a catastrophic failureninduced by local melting, delamination, evaporation, or some other change. We demonstrate that microma-nchined dielectric membranes show strong differences in their hydroxyl signatures as measured by Fourier-ntransform IR spectroscopy. The changes correspond to regions of high fluence u00013200 J/cm2u0002 from a Nd:YAGnlaser. It is found that the absorption peaks associated with OH decrease after laser treatment, indicating anreduction in the number of film hydroxyl groups. © 2009 Optical Society of America