Triply-Resonant Sum Frequency Conversion with Gallium Phosphide Ring Resonators

TL;DR

This paper demonstrates efficient triply-resonant sum frequency and difference frequency conversion in gallium phosphide ring resonators, enabling potential quantum communication applications with high conversion efficiencies.

Contribution

It introduces a novel integrated gallium phosphide resonator platform achieving high-efficiency sum and difference frequency conversion with potential for quantum networks.

Findings

8%/mW small-signal conversion efficiency from telecom and near-infrared to visible wavelengths

6.3% absolute power conversion efficiency at saturation pump power

Projected 7.2%/mW single photon conversion efficiency for difference frequency generation

Abstract

We demonstrate quasi-phase matched, triply-resonant sum frequency conversion in 10.6-um-diameter integrated gallium phosphide ring resonators. A small-signal, waveguide-to-waveguide power conversion efficiency of 8%/mW is measured for conversion from telecom (1536 nm) and near infrared (1117 nm) to visible (647 nm) wavelengths with an absolute power conversion efficiency of 6.3% measured at saturation pump power. For the complementary difference frequency generation process, a single photon conversion efficiency of 7.2%/mW from visible to telecom is projected for resonators with optimized coupling. Efficient conversion from visible to telecom will facilitate long-distance transmission of spin-entangled photons from solid-state emitters such as the diamond NV center, allowing long-distance entanglement for quantum networks.