High-Performance Tunable Vector Soliton Pulse Generation in Thulium-Holmium Co-Doped Fiber Lasers Utilizing a HNLF-GIMF Saturable Absorber

We present an experimental study on the generation of wavelength-tunable vector soliton pulses within a thulium-holmium co-doped fiber laser system, employing an absorber design that integrates a highly nonlinear fiber (HNLF) with a graded-index multimode fiber (GIMF) to achieve both laser mode-locking and continuous wavelength tuning. The system's polarization-independent saturable absorption capability results in the formation of group velocity locked vector solitons. By modulating a squeezing polarization controller at the GIMF junction, we have successfully demonstrated tunable soliton laser outputs spanning from 1910 nm to 1950 nm. Our findings indicate a correlation between wavelength tunability and intracavity power, specifically, as the intracavity power increases, the wavelength tuning range expands, suggesting a dynamic interplay between power levels and spectral characteristics that can be harnessed for precise control in spectroscopic applications. The laser system sustains mode-locking and preserves vector soliton properties across the entire tunable spectrum, establishing it as a versatile tunable vector soliton pulse laser platform. This innovative approach holds significant potential for applications in the fields of spectroscopy, biomedical imaging, and optical communication, marking a substantial advancement in fiber laser technology.