Large-area high-yield 1T-TiSe2 saturable absorber for wavelength-tunable ultrafast fiber lasers

Abstract

The production of high-yield saturable absorbers (SAs) with broad effective modulation zones remains a considerable challenge for the advancement of compact ultrafast fiber lasers. We present a fiber-end-integrated large-area high-yield 1T-TiSe₂ saturable absorber fabricated using chemical vapor transport (CVT) and accurate transfer technique. This strategic method achieves a three-order-of-magnitude enhancement in device area (tens of micrometers) compared to conventional liquid-phase exfoliation approaches. The comprehensive 1T-TiSe₂ has exceptional nonlinear optical properties, with a modulation depth of 20.1(±0.3)% and a saturation intensity of 7.29(±0.2) μJ/cm². The erbium-doped fiber laser enables the generation of stable femtosecond pulses with a compressed duration of 966 fs at a frequency of 13.84 MHz, marking a significant improvement over previously recorded picosecond durations. Additionally, a wavelength-tunable Q-switched laser has been demonstrated, including an 18 nm spectral range and maximum single-pulse energy of 62.4 nJ at 1565.8 nm. The findings highlight the exceptional potential of large-area 1T-TiSe₂ in integrating compact fiber laser design with high-energy ultrafast photonics, therefore establishing a versatile platform for tunable, high-performance pulsed laser systems.