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

https://phys.org/news/2022-11-semi-nonlinear-etchless-lithium-niobate-waveguide.html

"efficient SHG harnessing BIC semi-nonlinear waveguide constructed by electron-beam resist waveguide and thin-film silicon nitride and LN... Low propagation losses for FF and SH waves... achievement of MPM... Large nonlinear modal overlap for FF TM00 and SH TM01 mode... propagation modes guided by patterned low-refractive-index waveguide but confined in high refractive SiN/LN... TM-like modes immersed in high-loss continuous TE-like modes... can decrease propagation losses of both FF and SH"

Related: Strong-confinement low-index-rib-loaded waveguide structure for etchless thin-film integrated photonics
https://www.eurekalert.org/news-releases/1098481