Observation of Mid Infrared Domain-Wall Dark Pulses in an Er³⁺/Pr³⁺ Co-Doped InF₃-Glass Based Fiber Laser

In this letter, we demonstrate the generation of 2.7 μm dual-wavelength domain wall dark pulses in a homemade Er³⁺/Pr³⁺ co-doped InF₃ gain fiber. Bright-dark-dark and bright-dark pulse pairs were also observed by altering the fiber length. Our findings highlight the influence of net cavity dispersion and the gain-loss mechanism on the characteristics of dark pulses. By interpreting the dark soliton generation within a domain-wall framework, this research provides insights into the behavior of pulse dynamics in mid-infrared fiber lasers, offering potential for advancing mid-infrared pulse generation technologies.