GaTe-Based Saturable Absorber for Multi-Phenomenon Ultrafast Fiber Laser: Conventional Soliton, Q-Switched Mode-Locked, and H-Shaped Pulses

Abstract This paper presents a multimodal Erbium-doped fiber laser utilizing GaTe as saturable absorber (SA). The experiment investigated the nonlinear optical properties of topological material GaTe , and their modulation depth and saturation intensity are 13.8 % and 0.94 MW/cm². By adjusting the pump power and the polarization controller, the laser pulse transitions between different operating regimes, including conventional soliton (CS) , Q-switched mode-locked, and H-shaped pulses. The experiments reveal that the repetition frequency of Q-switched mode-locked and the width of H-shaped pulses vary with increasing pump power. This work highlights GaTe-based saturable absorbers as versatile ultrafast photonic modulation devices capable of generating multiple ultrafast phenomena, offering a promising platform for investigating novel ultrafast dynamics.