Stable Single-Longitudinal-Mode Fiber Ring Laser Using Topological Insulator-Based Saturable Absorber

A single-longitudinal-mode (SLM) fiber ring laser based on topological insulator (TI) Bi
₂
Te
₃
saturable absorber (SA) had been experimentally demonstrated. The TI: Bi
₂
Te
₃
nanosheets, which were fabricated through the bottom-up approach, were coated onto the microfiber as an efficient saturable absorber device to ensure the SLM operation. Combined with fiber Bragg grating, the output wavelength can be continuously tuned about 1 nm. Without any accurate cavity control, stable SLM operation without mode hopping had been conveniently achieved. Based on the Lorentzian fitting, the line-width was measured to be less than 10 kHz. The output power of SLM fiber laser can reach up to 23 mW, indicating that the proposed TI-based SA may be suitable for high-optical power SLM operation in the future.