Single-mode Chalcogenide Fiber: Fabrication and Supercontinuum Generation

glasses are well known for their unique characteristics in infrared (IR) and strong nonlinearities, endowing them as promising candidates for Mid-IR supercontinuum generation (SCG). Here, step-index As-S fiber with a small core was fabricated via twice-extrusion method. The fiber is single-mode when the propagating light wavelength is longer than 6.3 m. Loss baseline of the step-index fiber is about 1 dB/m. Zero-dispersion-wavelength (ZDW) of the fiber is located at near 5.2 m. By pumping the fiber with a femtosecond laser of optical parametric amplifier (OPA), Mid-IR SCG was investigated in multi-length scale fibers with different pumping wavelengths. Launching intense ultra-short pulses (~150 fs, 1 kHz) into a 23-cm-long fiber, Mid-IR SC spanning from 1.5 m to 8.7 m can be observed when pumping at a central wavelength of either 4.5 m or 5.2 m, corresponding to absorption peak at normal dispersion regime and ZDW, respectively. Besides, the spectra spanning would be extended in shorter fiber length under optimized pumping laser power. For ChG glass fiber, shorter fiber length is much more suitable for SC spanning than longer fiber length.