The passive Q-switching characteristics of a diode-pumped Tm,Ho:YAP laser at 2 μm based on a MoS ₂ saturable absorber (SA) is presented for the first time. Pulses as short as 435 ns under a repetition rate of about 55 kHz were generated at the incident pump power of 8.4 W, corresponding to the pulse peak power up to 11.3 W. This is, to the best of our knowledge, the highest pulse peak power, ever obtained from MoS ₂ based passively Q-switched 2-μm lasers. The experimental results sufficiently validated the feasibility of MoS ₂ as SA for solid-state 2-μm lasers.

Efficient diode-pumped Tm:LuAG lasers operating in continuous wave, dual-wavelength,and passive Q-switching regimes have been demonstrated. A maximum output power of 4.42 W with a beam quality of M ² ≤1.45 at 2021.2 nm was obtained, corresponding to a slope efficiency of 49.5%. Using a birefringent quartz plate, the Tm:LuAG laser emitted the highest output power of 2.3 W at dual-wavelength of 2022 and 2030 nm. With a SWCNT-SA employed as saturable absorber, passively Q-switched Tm:LuAG laser was realized, which generated the shortest pulses of 405 ns at 2021.6 nm and a maximum single pulse energy of 40.6 μJ at 2019.7 nm.

We proposed a passively stabilized Q-switched E r : L u 2 O 3 laser at 2845 nm, applying a MXene N b 2 C T x nanosheets saturable absorber prepared by the liquid-phase exfoliation method. The surface morphology and nonlinear properties of this nanosheet were systematically characterized. Average output power of 542 mW for the Q-switched laser was obtained under 7.26 W of absorbed pump power. Meanwhile, the Q-switched pulse duration was measured to be 223.7 ns with 142.9 kHz repetition rate corresponding to a peak power of 16.96 W.

A kind of saturable absorber (SA) based on layered MoSe ₂ nanosheets has been fabricated successfully by an ultrasound-assisted liquid phase exfoliation method. The as-prepared MoSe ₂ SA was characterized and employed as Q-switch in a diode-pumped Tm-doped crystalline all-solid-state laser at around 2 μm. A stable passively Q-switched 2 μm laser with a maximum pulse repetition rate of 158 kHz and a minimum pulse width of 520 ns was successfully realized. A maximum average output power of 1.19 W, corresponding to a maximum pulse energy of 12.7 μJ and pulse peak power of 21.8 W, has been obtained. It was the first demonstration of MoSe ₂ SA in realizing a solid-state 2 μm pulsed laser, to the best of our knowledge. The results confirmed the excellent ability and promising potential of MoSe ₂ SA as an optical modulator in generating high repetition rate and short pulsed laser at the midinfrared spectral band.

In the current study, layered metallic vanadium disulfide (VS₂) is fabricated by a liquid-phase exfoliation method, and its microstructures as well as optical characteristics are investigated. Based on first-principles calculations, the band structure and density of the states of both bulk T-VS₂ and monolayer H-VS₂ are illustrated, showing the metallic behavior with a zero band gap. By using VS₂ as the saturable absorber in a doubly Q-switched Tm:YAP laser with an EOM, the Q-switching laser pulses at 2 μm with 22 ns and 200 Hz are generated, corresponding to the single pulse energy of 755 μJ and the peak power of 34.3 kW. The coupled rate equations of the doubly Q-switched laser are given, and the numerical simulations agree with the experimental results. The results indicate that VS₂ is a promising nanomaterial due to its nonlinear optical property. The doubly Q-switched laser demonstrates a high level of performance in reducing pulse width and enhancing pulse peak power.

We report the surface morphology and the nonlinear absorption characteristics of MXene VCrC nanosheets prepared by the liquid-phase exfoliation method. The self-made MXene VCrC was applied as a saturable absorber in the Tm:YAP laser experiments, performing excellent Q-switching optical modulation characteristics in infrared range. With this absorber, a stable passively Q-switched 2 μm laser was achieved. Under an incident pump power of 3.52 W, a maximum output power of 280 mW was obtained with a T = 3% output coupler at a repetition frequency of 49 kHz. The corresponding pulse energy and peak power were 5.7 μJ and 6.6 W, respectively. The shortest pulse duration was 658 ns at the repetition rate of 63 kHz with a T = 1% output coupler.