400%/W second harmonic conversion efficiency in $\mathrm{14 \mu m}$-diameter gallium phosphide-on-oxide resonators

TL;DR

This paper demonstrates a highly efficient second harmonic generation in gallium phosphide resonators, achieving 400%/W efficiency, with potential for further enhancement through improved device coupling.

Contribution

It introduces a gallium phosphide on oxide platform with doubly-resonant, phase-matched ring resonators achieving record conversion efficiency for 1550 nm to 775 nm.

Findings

Achieved 400%/W second harmonic conversion efficiency.

Identified potential to increase efficiency by a factor of 20.

Demonstrated high quality factors and low mode volumes in resonators.

Abstract

Second harmonic conversion from 1550~nm to 775~nm with an efficiency of 400% W$^{-1}$ is demonstrated in a gallium phosphide (GaP) on oxide integrated photonic platform. The platform consists of doubly-resonant, phase-matched ring resonators with quality factors $Q \sim 10^4$, low mode volumes $V \sim 30 (\lambda/n)^3$, and high nonlinear mode overlaps. Measurements and simulations indicate that conversion efficiencies can be increased by a factor of 20 by improving the waveguide-cavity coupling to achieve critical coupling in current devices.