Tunable S+/S band Q-switched thulium-doped fluoride fiber laser using tungsten ditelluride (WTe2)

A tunable, passively Q-switched thulium-doped fluoride fiber laser (TDFFL) using a tungsten ditelluride (WTe2) thin film based saturable absorber (SA) was proposed and its operational efficacy demonstrated. At a maximum pump power of 250 mW, a Q-switched output at 1494 nm with a 3-dB bandwidth of 3 nm was obtained. The repetition rate was measured to be 36.5 kHz with a minimum pulse width of 3.7 µs, as well as a signal-to-noise ratio (SNR) of approximately 42 dB. Utilizing a tunable bandpass filter (TBPF), tunable Q-switching operation was achieved from 1459 to 1513 nm, giving a tuning range of 54 nm. The proposed laser would have significant use for systems operating in the S-band region, particularly for optical communications networks

1.3 μm passively Q-Switched bismuth doped fiber laser using Nb₂C saturable absorber

A tunable passively Q-switched fiber laser operating at 1.3 μm was demonstrated using bismuth-doped fiber (BDF) as the gain medium and using niobium carbide (Nb2C) as the saturable absorber (SA). The Nb2C was prepared using the solution casting method, and then fabricated into a film form for ease of integration into the laser cavity. Stable Q-switched pulses were observed as the pump power was increased from 820 to 1037 mW, generating pulses with increasing repetition rates from 10.1 kHz to 13.8 kHz and decreasing pulse widths from 17.54 to 7.58 μs. The all-fiber laser had a center wavelength at 1314 nm with a broad 3-dB bandwidth of 8.35 nm. The maximum output power and pulse energy of the Q-switched laser were 0.74 mW and 53.7 nJ, respectively. The laser was stable when tested for its long-term stability, where the peak frequency remained consistent at 13.8 kHz and the SNRs were maintained to be more than 60 dB throughout the entire test period. To the best of our knowledge, this is the first demonstration for a passively Q-switched fiber laser operating at 1.3 μm wavelength region using BDF as the gain medium

155 nm-wideband and tunable q-switched fiber laser using an MXene Ti3C2TXcoated microfiber based saturable absorber

MXenes have recently gained significant research interest due to its graphene-like structure that allows for a multitude of applications such as electronics, batteries and optics to be realized. In this work, stable Q-switched pulses are passively obtained from a thulium-doped fiber laser using an MXene Ti3C2TX coated microfiber as a saturable absorber (SA). The generated pulses have center lasing wavelength 1976 nm with a pulse repetition rate and pulse width ranging between 16 kHz to 59 kHz and 13 µs to 2.4 µs respectively. The generated pulses can be tuned over a wavelength range of 155 nm from 1895 nm to 2050 nm. The MXene based SA has signficant potential for generating pulsed laser outputs that will find uses in the areas of sensing, medicine and spectroscopy around the 'eye safe' 2 µm region