Low-Loss Adiabatic Silicon Chip-to-Fibre Couplers in the Mid-Infrared and Applications to Nonlinear Optics

Utilising novel, low-loss couplers (-0.58 dB), we characterise a potential $\text{TE}_{0}$ pair-photon source via stimulated four-wave mixing in a phase-matched, air-clad 220 nm silicon waveguide. This is the lowest insertion-loss nonlinear behaviour characterised at $2\ \mu \mathrm{m}$ wavelengths.