Usually, the event of WGM microresonators for built-in lithium niobate photonics is accompanied by the improvement in the LNOI preparation system. In the early stage, z-cut LN films were usually selected because of the restrictions of lithographic approaches. Bernal and co-employees enhanced the etching process to arrange a ridge waveguide https://lithium-niobate-crystal75184.dailyblogzz.com/33170524/lithium-niobate-crystal-an-overview