Simultaneous generation of four-wave mixing and stimulated Raman scattering in coupled lithium niobate microdisks mediated by second harmonic generation

TL;DR

This paper demonstrates a coupled lithium niobate microdisk system that enables simultaneous four-wave mixing and stimulated Raman scattering, enhancing nonlinear optical processes on-chip.

Contribution

It introduces a novel coupled microdisk structure fabricated with femtosecond laser micromachining that facilitates multiple nonlinear processes without strict phase matching.

Findings

Observed cascaded four-wave mixing and stimulated Raman scattering

Coupled microdisks improve nonlinear process efficiency

Rich nonlinear phenomena around second harmonic wavelength

Abstract

High quality lithium niobate thin film microresonators provide an ideal platform for on-chip nonlinear optics applications. However, the phase matching condition for efficient parametric process sets a high requirement for fabrication control. Here we demonstrate a photonic molecular structure composed of two strongly coupled lithium niobate microdisks of different diameters fabricated using femtosecond laser micromachining and focused ion beam milling. With a continuous wave excitation, rich nonlinear optical processes including cascaded four-wave mixing and stimulated Raman scattering were observed around the second harmonic wavelength. Our results indicate that the coupled microdisks form a superior system for nonlinear optical process.