100 MHz frequency-spacing switchable single-dual-frequency laser based on MXene QDs and a phase-shifted FBG

This paper introduces a mode-hop-free switchable single-dual-frequency fiber laser based on Ti 2 C MXene quantum dots and a phase-shifted fiber Bragg grating that exhibits two single-frequency operating states and one dual-frequency operating state for the first time. In our experiments, this laser has a threshold as low as 6 mW, a narrowest linewidth of 473.5 Hz, a relative intensity noise of −101.5 dB/Hz, an optical signal-to-noise ratio over 83 dB, and a slope efficiency that reaches 2.2% as a single-frequency fiber laser. Compared with other congeneric lasers, it has the best performance in terms of the threshold and signal to noise ratio. An easily detectable beat frequency of 122 MHz was measured when the laser was switched to be a dual-frequency fiber laser. This switchable single-dual-frequency fiber laser has the potential to be applied as a Lidar source for the measurement of static targets and moving subjects.