Molybdenum gallium carbide as saturable absorbers in 1.5-μm passive mode-locked fibre laser

Abstract

A saturable absorber (SA) is one of the important components in a passive mode-locked fibre laser configuration to attain picosecond- to femtosecond-competent ultrashort pulses for fulfilling the imperatives of industries, particularly engineering and life sciences. The substantiation of a newfound SA in the generation of mode-locked pulses utilising molybdenum gallium carbide (Mo2Ga2C)—a MAX phase nanomaterial—was authenticated in this work. A Mo2Ga2C SA thin film was fabricated via a simple solution with polyvinyl alcohol (PVA) as the hosting medium. Linear absorption, modulation depth, non-saturable absorption, and saturation intensity of the 17.141-μm Mo2Ga2C SA were found to be 8.29%, 19.82%, 9.21% and 2.85 kW/cm2, respectively. The fabricated Mo2Ga2C SA was then implemented into an erbium-doped fibre laser (EDFL) system to realise the eminently stable mode-locked fibre laser at a centre wavelength of 1559.2 nm and rudimentary signal-to-noise ratio (SNR) of 54.8 dB. The pulse repetition rate and pulse width were measured to be 968.72 kHz and 2.028 ps successively. The maximum pulse energy and peak power are 10.219 nJ and 24.12 mW. In corroboration with previous reports, the implementation of Mo2Ga2C as a mode-locker is propitious in validating the impressively stable and ultrafast nonlinear fibre laser system for further multidisciplinary applications, for instance, medical instrumentation, sensing and range finding, communication, and military due to its excellent optical, physical, thermal, and mechanical properties.