Ti3C2 MXene as an optical modulator in a Thulium/Holmium-doped fiber laser

Abstract

A Ti3C2 MXene based saturable absorber (SA) was demonstrated as an optical modulator to enable Q-switching and mode-locking in a Thulium-Holmium doped fiber laser (THDFL) cavity. Two different SA configurations were studied, with one SA in the form of a polyvinyl alcohol (PVA) polymer host thin film and the other one with the Ti3C2 MXene deposited along with a D-shaped fiber. For the case of the Ti3C2-PVA SA, only Q-switched was obtained at the threshold pump power of 126.4 mW. The generated Q-switched pulses had a center wavelength of 1961.4 nm with a maximum repetition rate and pulse energy of 42.5 kHz and 37.4 nJ and a minimum pulse duration of 2.4 μs. For the Ti3C2 MXene coated D-shaped fiber SA, mode-locking was achieved at a pump power of 209.9 mW with a center wavelength of 1915.9 nm and having a repetition rate and pulse width of 12.6 MHz and 1.89 ps, respectively. The experimental results indicate that the Ti3C2 MXene based SA could generate Q-switched pulses when in the form of a thin film but can only be used as a mode-locker when the SA material is coated along the surface of the D-shaped fiber.