superior performance with respect to speed and operation bandwidth than electronic based devices. [3-5] As a fundamental χ (3) process, FWM has found a wide range of applications in wavelength conversion, [6,7] optical frequency comb generation, [8,9] optical sampling, [10,11] quantum entanglement, [12,13] and many others. [14,15] Implementing nonlinear photonic devices in integrated form offers the greatest dividend in terms of compact footprint, high stability, high scalability, and mass-producibility. [1,2,16] Although silicon has been a leading platform for integrated photonic devices for many reasons, [1] including the fact that it leverages the well-developed complementary metal-oxide-semiconductor (CMOS) fabrication technologies, [17] its strong twophoton absorption (TPA) at near-infrared telecommunications wavelengths poses a fundamental limitation for devices operating in this wavelength region. Other CMOS compatible platforms such as silicon nitride (SiN) and doped silica [2,18] have a much lower TPA, although they still suffer from intrinsic limitation arising from a much lower Kerr nonlinearity. The increasing demand for high performing nonlinear integrated photonic devices has motivated the search for highly

We study the nonlinear optical properties of graphene integrated onto Si3N4 waveguides under picosecond and subpicosecond pulsed excitation at telecom wavelength. Saturable absorption of graphene under guided-mode excitation is measured, and the temporal effects related to the photoexcited carrier dynamics in graphene are highlighted. Thereafter, a model of photoexcited carriers in graphene is implemented into the nonlinear Schrödinger equation in order to simulate the pulse propagation across the hybrid graphene/Si3N4 waveguide. This allows us to extract phenomenological parameters of graphene saturable absorption in chip-based devices, which could provide some guidelines for the design of nonlinear elements in photonic integrated circuits.

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