Radiation hard mode-locked laser suitable as a spaceborne frequency comb

We report ground-level gamma and proton radiation tests of a passively mode-locked diode-pumped solid-state laser (DPSSL) with Yb:KYW gain medium. A total gamma dose of 170 krad(H2O) applied in 5 days generates minor changes in performances while maintaining solitonic regime. Pre-irradiation specifications are fully recovered over a day to a few weeks timescale. A proton fluence of 9.7610¹⁰c m^-2 applied in few minutes shows no alteration of the laser performances. Furthermore, complete stabilization of the laser shows excellent noise properties. From our results, we claim that the investigated femtosecond DPSSL technology can be considered rad-hard and would be suitable for generating frequency combs compatible with long duration space missions.