Mid-Infrared on-Chip Soliton Self-frequency Shift in Chalcogenide Glass Waveguide

Mid-infrared soliton lasers leveraging the Raman self-pumping induced soliton self-frequency shift (SSFS) effect offer continuously tunable, highly efficient, femtosecond coherent sources that are essential for applications such as spectroscopy, metrology, and quantum optics. However, despite significant advancements in fluoride and chalcogenide fiber platforms, realizing mid-infrared Raman soliton lasers on on-chip platforms remains challenging. In this study, the first experimental demonstration of a mid-infrared Raman soliton laser in an on-chip Ge28Sb12Se60 (GeSbSe) chalcogenide glass waveguide is presented. A fully fiberized femtosecond fiber laser, centered at 1.96 mu m and emitting 246 fs pulses at a 50 MHz repetition rate, is utilized as the pump source, establishing a fiber-to-chip configuration. The waveguides are meticulously fabricated using e-beam lithography and plasma etching, achieving high optical quality and precision in the mid-infrared regime. Through precise geometrical dispersion engineering, a Raman soliton laser is achieved that continuously tunes from 1960 to 2145 nm within a 32.5 mm long snakelike GeSbSe strip waveguide. The threshold for pump peak power is remarkably low, at just 14.1 W (3.47 pJ). Additionally, a more than one-octave-spanning near to mid-infrared supercontinuum (1320-2760 nm at 22.9 pJ), reinforced by the combined Kerr and Raman effects, is also realized, confirming the versatile performance of the proposed GeSbSe waveguide. These findings pave the way for mid-infrared on-chip Raman soliton lasers, highlighting their potential for power-efficient, low-cost, and field-deployable on-chip applications in the mid-infrared regime.