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

Abstract

We present a degenerate four-wave mixing experiment on a silicon nitride\n(SiN) waveguide covered with gated graphene. We observe strong dependencies on\nsignal-pump detuning and Fermi energy, i.e. the optical nonlinearity is\ndemonstrated to be electrically tunable. In the vicinity of the interband\nabsorption edge ($2|E_F|\\approx \\hbar\\omega$) a peak value of the waveguide\nnonlinear parameter of $\\approx$ 6400 m$^{-1}$W$^{-1}$, corresponding to a\ngraphene nonlinear sheet conductivity $|\\sigma_s^{(3)}|\\approx4.3\\cdot\n10^{-19}$ A m$^2$V$^{-3}$ is measured.\n