Semi-nonlinear etchless lithium niobate waveguide with bound states in the continuum

Lithium niobite (LN) with an ultra-wide optical transparent window has shown excellent nonlinear, electro-optic, acoustic-optic, piezoelectric, thermoelectric and photorefractive effects. It is an excellent platform for realizing χ(2) nonlinear photonic devices with low power consumption and high efficiency.