Nonlinear all-optical technology is an ultimate route for next generation ultra-fast signal processing of optical communication system. New nonlinear functionalities need to be implemented in photonics and complex oxides are considered as promising candidates due to their wide panel of attributes. In this context, Yttria-Stabilized Zirconia (YSZ) stands out thanks to its capability to be epitaxially grown on silicon, adapting the lattice for the crystalline oxides family of materials. We report for the first time a detailed theoretical and experimental study about the third order nonlinear susceptibility in crystalline YSZ. Via self-phase modulation induced broadening and considering the in-plane orientation of YSZ, we experimentally obtained an effective Kerr coefficient of n Y SZ 2 = 4.0 ± 2 · 10 −19 m 2 W −1 in a 8%mol. YSZ waveguide. In agreement with the theoretically predicted n Y SZ 2 = 1.3 · 10 −19 m 2 W −1 , the third order nonlinear coefficient of YSZ is comparable to the one of silicon nitride (SiN), already used in nonlinear optics. These promising results are a new step towards the implementation of functional oxides for nonlinear optical applications.< Leer menos