Sub-100 fs Tm:MgWO4 laser at 2017 nm mode locked by a graphene saturable absorber

Opt Lett. 2017 Aug 15;42(16):3076-3079. doi: 10.1364/OL.42.003076.

Abstract

We present the first sub-100 fs bulk solid-state laser in the 2-μm spectral range employing the monoclinic Tm3+-dopedMgWO4 crystal as an active medium. By applying a graphene-based saturable absorber and chirped mirrors for dispersion management, stable self-starting mode-locked operation at 2017 nm was achieved. Nearly Fourier-limited pulses as short as 86 fs featuring a bandwidth of 53 nm were generated at a repetition rate of 76 MHz. A pulse energy of 1.1 nJ was achieved at 87 MHz for a pulse duration of 96 fs. The mode-locked Tm3+:MgWO4 laser exhibits excellent stability with a fundamental beat note extinction ratio of 80 dBc above noise level.