Broadband Second Harmonic Generation in a z-Cut Lithium Niobate on Insulator Waveguide Based on Type-I Modal Phase Matching

We numerically investigate a second harmonic generation (SHG) in z-cut lithium niobate on insulator (LNOI) waveguide based type-I mode phase matching (MPM) between two fundamental modes. A overlap factor that is close to unity achieved and the normalized SHG efficiency reaches up 72.1% W−1cm−2 at telecommunication band, together with large spectral tunability of 2.5 nm/K. Moreover, bandwidth about 100 nm for broad 5 mm-long LNOI ridge demonstrated this scheme. This stratagem will inspire new integrated nonlinear frequency conversion methods versatile applications.