Octave-Spanning Supercontinuum Generation in As₂S₃-Silica Hybrid Waveguides Pumped by Thulium-Doped Fiber Laser

Broadband supercontinuum sources are of interest for various applications. The near-infrared region (1-3 μm) is specifically useful for biomedical diagnostics. One of the promising media for supercontinuum generation in the infrared region is the strongly guiding nonlinear waveguide with an arsenic trisulfide core (As2S3) and a fused silica cladding. The geometrical and chemical properties of such a waveguide allow to finely tune the dispersion landscape and nonlinearity through the core diameter variations. Here we report the generation of octave-spanning supercontinuum in As2S3-silica hybrid nanospike waveguides pumped by a thulium-doped all-fiber femtosecond laser and amplifier system at 1.9 μm wavelength. The widest supercontinuum was obtained in the wavelength range from 1.1 to 2.5 μm (full width at -10 dB) in the waveguide with a core diameter of 1.7 μm. Generation of significant dispersive waves, as well as third harmonics component, is observed. Numerical simulation shows that the generated supercontinua are coherent in the entire spectral range and can be exploited to create a self-referenced laser comb.