OPTOMAN’s high-reflectivity mirror coatings for ultrafast fibre lasers

High laser power levels call for high-power measures and OPTOMAN has developed high reflectivity IBS mirror coatings designed for ultrafast Yb:YAG, Yb:KYW/KGW, and Yb doped fiber lasers.

While high laser-induced damage threshold is a buzzword when talking femtosecond & picosecond optics, it is not (only) the nominal LIDT value that matters. The separation of laser damage modes – catastrophic and colour-change – is evident when measuring standard optics. The fatigue effect of colour-change damage becomes even more significant for high-power mirrors after prolonged radiation (>103 pulses).

Market-Standard 1030 nm mirrors feature >0.3 J/cm2, >0.4 J/cm2, >0.5 J/cm2 and similar values @ 1030 nm, 500 fs, 10 kHz. However, when mirrors are operated at extreme conditions with a large number of laser pulses per single irradiance sites, these mirrors suffer due fatigue and coating colour changes. This effect eventually ruins the laser beam profile.  Higher power coating options are available, where catastrophic LIDT value goes above 0.8 J/cm2 @ 1030 nm, 500 fs, 10 kHz. Fatigue (colour-change) effect is still there despite higher absolute LIDT.

The OPTOMAN R&D team developed SuperHero League ULLM5SHL mirrors where the fatigue (colour-change) effect is negligible and moreover LIDT increases. Technological developments are still in progress and coatings featuring super high LIDT with no colour-change degradation are under development.

Contact: Lukas Ceizaris