1D/2D DWCNT/MoS₂ mixed-dimensional heterostructure as saturable absorber in passively Q-switched Tm:YLF laser

One-dimensional (1D) materials can be integrated with two-dimensional (2D) materials to form mixed-dimensional heterostructures. This combination gives rise to numerous intriguing physical phenomena in 1D/2D heterostructures, making them promising candidates for constructing novel photonic and electronic devices. In this study, a 1D/2D DWCNT/MoS₂ mixed-dimensional heterostructure was fabricated using the two-step CVD method, and its nonlinear absorption properties were investigated. For the first time, a 1.9 μm passively Q-switched (PQS) thulium-doped solid-state nanosecond pulsed laser based on a 1D/2D DWCNT/MoS₂ saturable absorber (SA) was achieved. At the pump power of 12.2 W, the PQS laser delivered a maximum output power of 380 mW with a slope efficiency of 3.8 % at 1904.5 nm. The narrowest pulse width was 830 ns at the pulse repetition rate of 40 kHz, corresponding to the maximum pulse energy of 9.5 μJ. The experimental results demonstrate that the 1D/2D DWCNT/MoS₂ mixed-dimensional heterostructure exhibits excellent optical modulation performance, showing significant potential for applications in mid-infrared pulsed lasers.