Niobium carbide (Nb₂C) MXene as a saturable absorber to assist in the generation of a wavelength tunable passively Q-switched fiber laser

Niobium carbide (Nb₂C), a new member of the MXene family, is proposed as a potential saturable absorber (SA) material. Stable Q-switched pulses were established in the C-band wavelength region upon employing a Nb₂C/PVA film-based SA in the erbium-doped all-fiber ring cavity. The generated EDF laser operated at a wavelength of 1558.73 nm with a corresponding 3 dB bandwidth and signal-to-noise ratio of 2.8 nm and 53.8 dB. A maximum pulse repetition rate and pulse energy of 75.19 kHz and 15.63 nJ were observed at a maximum pump power of 224.5 mW. Interestingly, the emission spectra can be continuously tuned across 44 nm ranging from 1522.32 nm to 1566.07 nm by controlling the tunable band pass filter that has been introduced in the laser cavity. Our findings reflect the feasibility of using Nb₂C as an excellent broadband SA material that underpins new opportunities for photonic technology and other potential applications in nonlinear optics. (letter)