Nanosecond-Pulsed, Dual-Wavelength Passively Q-Switched c-Cut Nd:YVO Laser Using a Few-Layer Bi

We demonstrate for the first time, to the best of our knowledge, a dual-wavelength nanosecond-pulsed Nd:YVO₄ laser passively Q-switched by a topological-insulator (TI) Bi₂Se₃ saturable absorber (SA). The few-layer Bi₂Se₃ nanosheets are fabricated by the liquid-phase exfoliation technique, and are then coated on the output mirror of a diode-pumped c-cut Nd:YVO₄ laser. The synchronized Q-switching operation at 1066.6 and 1066.8 nm is successfully achieved. The Q-switched repetition rate is tunable in a wide range of 1-135 kHz, and the maximum pulse energy is obtained to be 0.56 μJ (corresponding to the peak power of 1.87 W). The obtained pulse width can be as narrow as 250 ns, which is the shortest one from the reported TI-based Q-switched lasers.