Few-layer Bi₂Te₃: an effective 2D saturable absorber for passive Q-switching of compact solid-state lasers in the...

An experimental investigation was carried out to evaluate the potential of few-layer Bi₂Te₃ topological insulator in use as a saturable absorber for passive Q-switching of compact solid-state lasers in the 1-μm spectral region. By incorporating a sapphire-based few-layer Bi₂Te₃ sample into a Yb:LuPO₄ laser that was formed with a 4-mm plane-parallel resonator, we realized efficient, high-power, high-repetition-rate pulsed laser operation. Depending on the output coupling utilized, single- or dual-wavelength laser action could be achieved. A maximum output power of 5.02 W at 1014.5 nm was produced at a pulse repetition rate of 1.67 MHz, with an optical-to-optical efficiency of 41% and a slope efficiency of 54%; while operating at 1004.9/1012.7 nm, the pulsed laser could produce an output power of 3.94 W at 1.38 MHz, with a pulse duration being as short as 34 ns. The largest pulse energy and highest peak power achieved were 3.0 μJ and 85.3 W. The results demonstrated in our experiment reveal the great potential of the few-layer Bi₂Te₃ topological insulator in the development of pulsed compact solid-state lasers in the 1-μm region.