High Quality Ternary Crystal Ta ₂ Ni ₃ Te ₅ as a Fiber-Integrated Saturable Absorber for Ultrafast Fiber Laser

The development of high-performance saturable absorbers (SAs) combining strong nonlinear optical response, robust environmental stability, and ease of fiber integration remains critical for advancing compact ultrafast fiber laser systems. Here, a fiber integrated SA was demonstrated based on the high quality ternary crystal Ta 2 Ni 3 Te 5, synthesized by chemical vapor transport and transferred onto fiber facets via a precision dry-transfer technique. Benefiting from its van der Waals layered structure and unique electronic topology, Ta 2 Ni 3 Te 5 based SA exhibits a modulation depth of 19.98% and a saturation intensity of 0.74 GW/cm 2 at 1.55 μm excitation. When incorporated into an erbium-doped fiber laser cavity, the Ta 2 Ni 3 Te 5 –SA enables both stable dual-wavelength Q-switching and robust mode-locking. In the mode-locked regime, the laser delivers picosecond pulses (2.07 ps), with a repetition rate of 10.66 MHz. It is worth noting that the output power of the pulsed laser is up to 24.6 mW, and the signal-to-noise ratio is as high as 76.8 dB. Moreover, the SA exhibits strong optical damage resistance and maintains stable performance after prolonged storage, underscoring its environmental robustness. This work establishes Ta 2 Ni 3 Te 5 as a promising nonlinear optical material for ultrafast photonics and provides a practical pathway toward high-performance, fiber pulsed laser sources.