Second harmonic generation in gallium phosphide photonic crystal nanocavities with ultralow continuous wave pump power

TL;DR

This paper demonstrates highly efficient second harmonic generation in gallium phosphide photonic crystal nanocavities using ultralow continuous wave pump power, highlighting potential for integrated low-power nonlinear optical devices.

Contribution

The study reports the first demonstration of second harmonic generation in GaP nanocavities with nanowatt input power and high conversion efficiency, advancing integrated nonlinear photonics.

Findings

Second harmonic at 750 nm observed with nanowatt input power.

Conversion efficiency of 430%/W achieved.

GaP's large band gap reduces absorption loss.

Abstract

We demonstrate second harmonic generation in photonic crystal nanocavities fabricated in the semiconductor gallium phosphide. We observe second harmonic radiation at 750 nm with input powers of only nanowatts coupled to the cavity and conversion efficiency $P_{\rm out}/P_{\rm in, coupled}^2 = 430%/{\rm W}$. The large electronic band gap of GaP minimizes absorption loss, allowing efficient conversion. Our results are promising for integrated, low-power light sources and on-chip reduction of input power in other nonlinear processes.