Distributed Bragg reflector waveguide laser on erbium doped thin film lithium niobate on insulator

With the advancement and increasing scalability of Lithium Niobate-on-insulator (LNOI) based photonic integrated circuits (PICs), the development of LNOI on-chip light source with great compatibility has become an urgent task. Erbium ions are often introduced into LNOI to achieve efficient C-band luminescence, as the indirect bandgap of lithium niobate makes it an unsuitable host material for light emission. In this work, we propose an LiNbO ₃ : Er ³⁺ waveguide laser based on the distributed Bragg reflector (DBR) cavity. By employing silicon nitride loading strips to realize the lateral confinement of the optical mode, we discussed the impact of resonator and Bragg grating structural designs on laser performance, and the laser with high confinement factor (78.2%) is attainable. It has the TE mode lasing around 1533 nm, with laser yield efficiencies over 5% and pump threshold less than 0.1 mW in a 10-mm-long DBR cavity. This and highly compatible waveguide laser will find potential applications in LNOI based large scale PICs.