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 Er<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3+</sup>/Pr<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3+</sup> co-doped InF<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> 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.