On-chip nonvolatile tunable second-harmonic-generation through integration of NbOBr2

The integration of second harmonic generation (SHG) into silicon photonics (SiPh) is limited by the lack of CMOS-compatible nonlinear material. And fixed response without tunability significantly obstacle the practical application of NLO process. The superior 2D material with specific stacking order enable intrinsic second-order susceptibility (<i>&chi;</i>⁽²⁾) which stems from the centrosymmetry-breaking structure. Although some transition metal dichalcogenides (TMDCs) and hexagonal boron nitride (hBN) has enabled great SHG response, their even-odd layer-dependent SHG response limit the promise for integration to SiPh platform. Furthermore, the lack of tunability in system curtail the further application of NLO process. Here, we demonstrate the first electrically tunable on-chip nonlinear photonic device with efficient SHG conversion from near-infrared light, enabled by integrating 2D niobium oxide dibromide (NbOBr₂) into an optical cavity-based SiN photonic platform. The SHG response comes from the combination of NbOBr₂’s <i>&chi;</i>⁽²⁾ and on-chip cavity’s enhancement for pump light, and the nonvolatile tunability stems from the in-plane ferroelectricity-induced loss change in cavity.