Tunable-wavelength second harmonic generation from GaP photonic crystal cavities coupled to fiber tapers

We demonstrate up to 30 nm tuning of gallium phosphide photonic crystal cavities resonances at aproximately 1.5 microm using a tapered optical fiber. The tuning is achieved through a combination of near-field perturbations and mechanical deformation of the membrane, both induced by the fiber probe. By exploiting this effect, we show fiber-coupled second harmonic generation with a tuning range of nearly 10 nm at the second harmonic wavelength of approximately 750 nm. By scaling cavity parameters, the signal could easily be shifted into other parts of the visible spectrum.