Unidirectional frequency doubling laser based on lithium niobate on insulator

Abstract

The unidirectional transmission of on-chip light sources is crucial for constructing photonic integrated circuits (PICs). Establishing exceptional points (EPs) or exceptional surfaces (ES) represents a significant approach to achieving unidirectional transmission. We study an on-chip integrated unidirectional frequency doubling laser based on the second-order optical nonlinearity of lithium niobate and the realization of ES through asymmetrical mode coupling in the microcavity. The device integrates frequency conversion and unidirectional laser transmission into a single module, compatible with the realization of multi-functional PICs. Moreover, the performance of the device exhibits high tolerance to parameter variations. The proposed device exhibiting stable performance and ease of fabrication offers novel insights into the development of PICs.