Stimulated Brillouin scattering by surface acoustic waves in lithium niobate waveguides

TL;DR

This paper demonstrates through numerical simulations that lithium niobate waveguides can support surface acoustic waves that enable strong backward stimulated Brillouin scattering, with potential for integrated photonic applications.

Contribution

It provides the first detailed anisotropic simulation of surface acoustic wave-induced Brillouin scattering in lithium niobate waveguides, including roto-optic effects.

Findings

Surface acoustic waves are confined in LNOI waveguides.

Strong backward stimulated Brillouin scattering is achievable.

Photoelasticity dominates the Brillouin gain, reaching 0.43 W$^{-1}$m$^{-1}$.

Abstract

We numerically demonstrate that Lithium Niobate on Insulator (LNOI) waveguides may support confined short-wavelength surface acoustic waves that interact strongly with optical fields through backward stimulated Brillouin scattering in both $Z$ and $X$-cut orientation. We conduct fully anisotropic simulations that consider not only moving boundary and photoelastic forces, but also roto-optic forces for the Brillouin interaction. Our results indicate that photoelasticity dominates the Brillouin gain and can reach as high as $G_{B}/Q_{m}$ = 0.43 W$^{-1}$m$^{-1}$ in standard ridge waveguides