Continuous wave and rhenium disulphide-based Nd:GdTaO₄ laser under direct pumping

In this paper, a continuous wave (CW) and rhenium disulphide (ReS₂) passively Q-switched Nd:GdTaO₄ laser under the pump at 879 nm was firstly reported. CW output characteristics under indirect 808 nm pumping and direct 879 nm pumping were investigated, respectively. By comparison with indirect pumping, the direct pump at 879 nm effectively relieved thermal lenses effect. Under direct pumping, the maximum CW output power was 5.1 W with slope efficiencies (η_s) of 48.6%. In the indirect pumping a maximum CW output power of 4.3 W was obtained, corresponding to η_s of 41.2%. A ReS₂ nanosheet was utilized to achieve the pulsed laser output. At absorbed pump power of 7.1 W, the highest repetition rate, narrowest pulse width, maximum average output power, single pulse energy, and peak power reached 67 kHz, 230 ns, 1 W, 14.93 μJ, and 64.9 W, respectively.