Integrated lithium niobate single-mode lasers by the Vernier effect

Microcavity lasers based on erbium-doped lithium niobate insulator (LNOI), which are key devices for LNOI integrated photonics, have attracted much attention recently. In this Letter, we report the realization of a C-band single-mode laser using Vernier effect in two coupled Erbium-doped microrings with different radii under pump 980-nm continuous laser. The laser, operating stably over large range pumping power, has threshold ~200 {\mu}W and side-mode suppression ratio exceeding 26 dB. high-performance will promote development photonics.