Optical and laser performances of a layered ReSe2 saturable absorber for a 2-µm solid laser

Abstract In this paper, a dispersion solution of rhenium diselenide (ReSe2) was prepared using an ultrasonic decomposition method and prepared for use as a saturable absorber (SA) mirror by spin-coating. The optical characteristics of the ReSe2 SA were characterized to acquire those parameters which were saturated at 2 μm. A passively mode-locked (PML) Tm:YAG laser with an ReSe2 SA was first demonstrated in an experiment. Under a continuous wave (CW) regime, a 1940-mW output power was achieved at 2013.8 nm with a pump power of 22.4 W. In PML mode, a 320-mW average output power and a 580.5-ps pulse duration at 203.1 MHz were acquired from the PML Tm:YAG laser with an output wavelength of 2012.6 nm, corresponding to a pulse energy of 1.58 nJ and an optical-optical conversion efficiency of 2.2%.