Supermode-based second harmonic generation in a nonlinear interferometer.

David Barral,Sébastien Tanzilli,Nadia Belabas,Virginia D’Auria,Florent Doutre,Juan Ariel Levenson,Sorin Tascu,Tommaso Lunghi,Alicia Petronela Rambu,Kamel Bencheikh

doi:10.1364/oe.435281

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 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.

Highlights

Strong bipartite and four-partite continuous-variable entanglement are predicted in a second harmonic generation (SHG) configuration when pump light at the fundamental frequency is in propagation eigenmodes
(1), due the linear coupling effect, the pump will be present at both inputs of the nonlinear directional coupler (NDC)
Whatever the injected waveguide, the pumps arriving at the NDC inputs have equal amplitudes and a π/2 relative phase

Summary

Introduction

The nonlinear directional coupler (NDC) is a core device in integrated optics without analog in bulk optics: evanescent coupling and nonlinear interaction effects are intertwined instead of being sequential as it is the case for daisy-chained beamsplitters and active nonlinear elements.The NDC has been widely studied in the classical regime for ultrafast all-optical switching [1,2,3,4,5,6,7,8,9].Recently, the χ (2) NDC has found a flourishing field of application: quantum optics [10].Its key strengths in quantum information processing as a source of entangled photons and entangled field quadratures are actively explored [11,12,13,14,15,16]. In this paper we overcome those experimental issues for the NDC, an array of two nonlinear waveguides, through a fully-fibered pump shaper and demonstrate supermode-based SHG through a -designed integrated nonlinear interferometer made of linear (LDC) and nonlinear (NDC) directional couplers.

Results

Conclusion