Tunable S-Band Q-Switched Fiber Laser Using Bi2Se3 as the Saturable Absorber

This paper describes a successful demonstration of S-band region wavelength output generated via a tunable Q-switch fiber laser with the topological insulator (TI) Bi₂Se₃ as a saturable absorber (SA). The modulation depth of the TI was measured as 11.1%, whereas the utilized 980-nm laser source operated at 100 mW pump power. By inserting the TI-SA between two ferrules and utilizing a tunable bandpass filter (TBPF), a stable and tunable Q-switching operation was achieved over the S-band wavelength region from 1493.6 to 1508.9 nm, wherein pulsewidth was 7.6 μs, and the tunable repetition rate ranged from 26.1 to 36.6 kHz. The Q-switched pulses had maximum pulse energy of 6.1 nJ, as measured from 2.5% of the cavity output. The results provide evidence that a TI-based SA is suitable for pulsed laser operation in the S-band wavelength region and offers potential for further development as an ultrabroadband photonics device.