High dispersive mirrors for the high energy lasers

We report on two newly developed types of dispersive mirrors. First type covers range of 1027-1033 nm, has 99.9% reflectance and -4500 fs
²
of group delay dispersion (GDD). When implementing these mirrors in Yb:YAG disk oscillator we observe changes on the surface of the mirrors due to thermal effects. Second type is high dispersive mirror (HDM) which provides GDD of -3000 fs
²
and covers wavelength range of 1020-1035 nm. The fabricated mirrors have reflectance 99.97%. We haven't observed any thermal effects on the second type of HDM, it behaves similar to non-dispersive quarter wave stack mirrors. This HDM were successfully implemented in an Yb:YAG disk oscillator over 1 kW of intracavity circulated power. The reported mirrors expand possibilities of multilayer optics. The mentioned large GDD allows to compress the nanosecond pulses down to femtosecond range.