Diode-pumped mode-locked Tm:LuAG 2 μm laser based on GaSb-SESAM

Ultrafast 2μm lasers are capturing a growing interest for the use as pump and seed sources in optical parametric systems operating in the mid-IR, for IR super-continuum generation, and for time-resolved spectroscopy. However, the demonstration of solid-state ultrashort 2 μm laser based on passive mode-locking lacks behind similar developments with established gain media, at 1 μm for example, partially due to a lack of technological developments of the key components — saturable absorbers (SAs) [1]. In the mid-IR wavelength region, GaSb material exhibits exceptional advantages. The GaSb-based SESAMs comprising GaInSb/GaSb (Quantum-wells) QWs exhibit a fast sub-ps absorption recovery time as a result of the significantly stronger Auger recombination, so a fast relaxation time without the need for ion implantation or low-temperature growth, combined with possibility to vary the number of QWs almost without any strain-related limitation, makes GaSb-based SESAMs attractive for mode-locking at 2 μm.