High-confinement gallium nitride-on-sapphire waveguides for integrated nonlinear photonics.

We demonstrate a highly effective nonlinearity of 7.3  W m in a high-confinement gallium nitride-on-sapphire waveguide by performing four-wave mixing characterization at telecom wavelengths. Benefitting from a high-index-contrast waveguide layout, we can engineer the device dispersion efficiently and achieve broadband four-wave mixing operation over more than 100 nm.