Resonant second harmonic generation between 1550 nm and 775 nm with outside
efficiency >4.4×10−4mW−1 is demonstrated in a gallium
phosphide microdisk cavity supporting high-Q modes at visible (Q∼104)
and infrared (Q∼105) wavelengths. The double resonance condition was
satisfied through intracavity photothermal temperature tuning using ∼360μW of 1550 nm light input to a fiber taper and resonantly coupled to
the microdisk. Above this pump power efficiency was observed to decrease. The
observed behavior is consistent with a simple model for thermal tuning of the
double resonance condition.Comment: 6 pages, 4 figure