Efficient telecom to visible wavelength conversion in doubly resonant GaP microdisks

TL;DR

This paper demonstrates efficient second harmonic generation in gallium phosphide microdisks at telecom and visible wavelengths, achieved through intracavity thermal tuning of double resonance conditions, with high quality factors at both wavelengths.

Contribution

It introduces a method for resonant frequency tuning in GaP microdisks using intracavity photothermal effects to enable efficient wavelength conversion.

Findings

Achieved > 4.4×10^{-4} mW^{-1} SHG efficiency

Supported high-Q modes at visible and infrared wavelengths

Demonstrated thermal tuning of double resonance condition

Abstract

Resonant second harmonic generation between 1550 nm and 775 nm with outside efficiency $> 4.4\times10^{-4}\, \text{mW}^{-1}$ is demonstrated in a gallium phosphide microdisk cavity supporting high-$Q$ modes at visible ($Q \sim 10^4$) and infrared ($Q \sim 10^5$) wavelengths. The double resonance condition was satisfied through intracavity photothermal temperature tuning using $\sim 360\,\mu$W 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.