Efficient four-wave mixing at the nanofocus of integrated organic gap plasmon waveguides on silicon

TL;DR

This paper demonstrates highly efficient four-wave mixing in integrated organic gap plasmon waveguides on silicon, enabling compact and broadband nonlinear optical processes with relaxed phase matching requirements.

Contribution

The work introduces a novel integrated plasmonic waveguide design that achieves micron-scale efficient four-wave mixing by nanofocusing light in a nonlinear organic polymer.

Findings

Efficient four-wave mixing at micron-scale interaction lengths.

Strong light confinement enhances nonlinear response.

Potential for compact, broadband integrated nonlinear photonics.

Abstract

Nonlinear optics, especially frequency mixing, underpins modern optical technology and scientific exploration in quantum optics, materials and life sciences, and optical communications. Since nonlinear effects are weak, efficient frequency mixing must accumulate over large interaction lengths restricting the integration of nonlinear photonics with electronics and establishing limitations on mixing processes due to the requirement of phase matching. In this work we report efficient four-wave mixing over micron-scale interaction lengths at telecoms wavelengths. We use an integrated plasmonic gap waveguide on silicon that strongly confines light within a nonlinear organic polymer in the gap. Our approach is so effective because the gap waveguide intensifies light by efficiently nanofocusing it to a mode cross-section of a few tens of nanometres, generating a nonlinear response so strong that efficient four-wave mixing accumulates in just a micron. This is significant as our technique opens up nonlinear optics to a regime where phase matching and dispersion considerations are relaxed, giving rise to the possibility of compact, broadband, and efficient frequency mixing on a platform that can be integrated with silicon photonics.