150-ps broadband low dispersion mirror thin film damage competition

摘要

Broadband low dispersion mirrors are fluence-limiting and pulse-shape-limiting components in short pulse lasers. To better understand the current technology state of broadband low dispersion mirrors, a laser damage competition was held at the 2015 Laser Damage Conference. Participants were asked to submit mirrors that met a minimum reflection of 99.5% at 45 degrees incidence angle at "P" polarization with a Group Dispersion Delay (GDD) of ＜± 100 fs~2 over a spectral range of 773 nm ± 50 nm. The participants selected the coating materials, design, and deposition method. Laser damage testing was performed using the raster scan method with a 150 ps pulse length on a single testing facility to enable a direct comparison among the participants. GDD measurements were performed to validate specification compliance. Unfortunately nearly half of the submitted samples were found to not meet the GDD specifications. Details of the deposition processes, cleaning method, coating materials, and layer count are also shared.