Nonlinear optics in gallium phosphide cavities: simultaneous second and third harmonic generation

We demonstrate the simultaneous generation of second and third harmonic signals from a telecom wavelength pump in gallium phosphide (GaP) microdisk. Using analysis power scaling both outputs calculations nonlinear cavity mode coupling factors, we study contributions to signal direct cascaded sum frequency processes. find that despite relatively high material absorption GaP at wavelength, these processes can be significant, with relative magnitudes depend closely on detuning between wavelengths modes.