Passively Mode-Locked Tm:YAP Laser Utilizing a Mo2TiAlC2 MAX Phase Saturable Absorber for Modulation

This study reports a novel MAX phase material, Mo2TiAlC2, as a passively mode-locking (PML) saturable absorber (SA) for a Tm:YAP laser operating in the 2 μm wavelength range. The systematic characterization of its nonlinear optical properties was quantitatively analyzed using I-scan methodology, demonstrating a significant modulation depth of 3.5%, which indicated strong nonlinear optical activity. Within the realm of optimal cavity conditions, a remarkable performance by the PML configuration can be discerned. A stable pulsed emission was manifested at 1937 nm, wherein an average output power reaching 620 mW was achieved. A pulse temporal span of 989.5 ps was acquired with a corresponding repetition frequency of 103.1 MHz, indicating robust mode-locked synchronization. Notably, the beam quality factors (M2) along the orthogonal spatial axes were observed with values measuring 1.12 and 1.18, respectively, indicating propagation characteristics close to those of diffraction-limited beams.