Supermode-based second harmonic generation in a nonlinear interferometer

TL;DR

This paper demonstrates supermode-based second harmonic generation in an integrated nonlinear interferometer, enabling mode-selective SHG with potential applications in scalable quantum and classical photonic circuits.

Contribution

It introduces a novel supermode-based SHG technique in integrated nonlinear interferometers using fibered pump shaping and phase control.

Findings

Successful demonstration of mode-selective SHG using symmetric and anti-symmetric modes

Implementation of robust phase setting scheme for mode selection

Potential for multiplexing in quantum and classical photonic circuits

Abstract

We demonstrate supermode-based second harmonic generation in an integrated nonlinear interferometer made of linear and nonlinear directional couplers. We use a fully-fibered pump shaper to demonstrate second harmonic generation pumped by the symmetric or anti-symmetric fundamental spatial modes. The selection of the pumping mode and thus of a specific SHG spectral profile is achieved through the selection of the fundamental wavelength and via a robust phase setting scheme. We use two methods: either post-selecting or actively setting the pumping mode. Such a modal phase matching paves the way for classical and quantum applications of coupled nonlinear photonic circuits, where multimode excitation, encoding and detection are a route for multiplexing and scaling up light-processing.