# Electrically Tunable Optical Nonlinearities in Graphene-Covered SiN Waveguides Characterized by Four-Wave Mixing

## TL;DR

This study demonstrates electrically tunable optical nonlinearities in graphene-covered silicon nitride waveguides using four-wave mixing, with significant nonlinear enhancement near the interband absorption edge.

## Contribution

The paper reports the first experimental observation of electrically tunable nonlinear optical response in graphene-covered SiN waveguides via four-wave mixing.

## Key findings

- Nonlinear parameter of ~6400 m$^{-1}$W$^{-1}$ near absorption edge
- Nonlinear sheet conductivity of ~4.3×10$^{-19}$ A m$^2$V$^{-3}$
- Strong dependence on signal-pump detuning and Fermi energy

## Abstract

We present a degenerate four-wave mixing experiment on a silicon nitride (SiN) waveguide covered with gated graphene. We observe strong dependencies on signal-pump detuning and Fermi energy, i.e. the optical nonlinearity is demonstrated to be electrically tunable. In the vicinity of the interband absorption edge ($2|E_F|\approx \hbar\omega$) a peak value of the waveguide nonlinear parameter of $\approx$ 6400 m$^{-1}$W$^{-1}$, corresponding to a graphene nonlinear sheet conductivity $|\sigma_s^{(3)}|\approx4.3\cdot 10^{-19}$ A m$^2$V$^{-3}$ is measured.