EnhancedΧ⁽²⁾ in CMOS-compatible Al_1-xSc_xN thin films

Advancement in large-scale production of integrated photonic devices requires strongly nonlinear materials that are CMOS-compatible. While most materials require a trade-off between compatibility and nonlinearity, Al_1-xSc_xN is a CMOS-compatible alloy that exhibits enhanced second-order optical susceptibility (Χ⁽²⁾) with increased Sc concentration. Here, we present second harmonic generation measurements of Al_1-xSc_xN thin films that demonstrate greatly enhanced Χ⁽²⁾ values. For a sample with 36% Sc, we observe one Χ⁽²⁾ component, d₃₃, to have a value of 62.3±5.6 pm/V, which is increased by over an order of magnitude compared to intrinsic AlN and by a factor of two compared to lithium niobate. Though propagation loss also increases with Sc concentration, the percentage of Sc can be tuned for particular applications to balance loss and strong nonlinearity. The large Χ⁽²⁾ and CMOS-compatibility of this material make it a promising avenue for scalable production of nonlinear photonic devices.