Mid-IR broadband supercontinuum generation from a suspended silicon waveguide.

Mid-infrared light provides numerous unexpected opportunities in scientific discoveries because this wavelength region covers the fingerprints of various molecular vibrational resonances. However, the light generation efficiency and bandwidth have been a long-standing bottleneck which has limited the development so far. Moreover, the light source that can be integrated with other components such as wavelength filters, detectors, and electronics, will be the key factor toward the future practical applications. Here, we propose an all-air-cladding silicon-rib waveguide to experimentally reveal the nonlinear performance of supercontinuum generation. By tuning the waveguide dispersion parameters with simulation, a continuous broad spectrum of 1.32 octave (2-5 μm) was observed with a pump pulse wavelength of 4 μm. To further investigate our device characteristics, multiple conditions were set by varying the interaction length, pump power, and waveguide dimension, which revealed the nonlinear phenomenon in the waveguide.