Thermally Driven Soliton Tuning and State Transition in Bi₂TeSe₂-Based Ultrafast Fiber Lasers for Encoding Applications

We demonstrate a thermally tunable mode-locked fiber laser integrating a polarization-sensitive SMF–PMF–SMF modulator and a Bi₂TeSe₂ saturable absorber. By controlling the PMF temperature, reversible switching among conventional, dissipative, and bound-state solitons is achieved. The wavelength tuning ranges are about 5 nm and 2.8 nm for conventional and dissipative solitons, respectively, with a tuning efficiency of 0.35 nm/℃. Numerical simulations based on temperature-induced birefringence variation reproduce the observed dynamics. Furthermore, a wavelength-encoding scheme utilizing thermally driven soliton shifts is proposed, providing a feasible approach for soliton-state-controlled optical communication.