Advancing Q-switched pulse generation in the 1.9 µm wavelength region using novel thulium-doped fiber gain medium and MXene Nb2CTx saturable absorber

This paper presents the first demonstration of a Q-switched Thulium-doped fiber laser (TDFL) utilizing our newly developed Thulium-doped fiber (TDF) and a MXene niobium carbide - polyethylene oxide (Nb2CTx-PEO) thin film as a gain medium and saturable absorber (SA), respectively. The TDF core glass contains 6.15 wt% Al2O3, 2.2 wt% Y2O3, 0.47 wt% Tm2O3, 2.12 wt% GeO2, 1.57 wt% HfO2 and 0.05 wt% Bi2O3 with the absorption of 30 dB/m at 1550 nm. The outcome was the realization of a stable pulsed laser operating at a central wavelength of 1888.3 nm. The Q-switched pulses exhibited a maximum repetition rate of 46.7 kHz and a minimum pulse width of 1.995 µs at a pump power of 731.41 mW. The Q-switched operation maintained a signal-to-noise ratio (SNR) of 45 dB, confirming its stability. This breakthrough highlights the laser system's potential for diverse applications, including free-space optical communication, spectroscopy, and medical fields.