Efficient Integrated Amplifier-Assisted Laser on Erbium-Doped Lithium Niobate

A light source is an indispensable component in on-chip systems. Compared with hybrid or heterogeneous integrated laser, monolithically integrated laser is more suitable for high-density photonic integrated circuits because of the capability of large-scale manufacturing, lower active-passive coupling loss, and less test complexity. Recent years have seen the spark of research on the rare-earth ion-doped thin film lithium niobate, and demonstrations have been made in both classical and quantum chips. However, low output power and limited quantum emitting efficiency hinder the application of the chip-scale laser source based on this platform. Here a highly efficient integrated laser assisted by an amplifier is proposed and experimentally prepared on Erbium-doped thin film lithium niobate. A slope efficiency of 0.43% and a linewidth of 47.86 kHz are obtained. The maximum integrated laser power is 7.989 μW. Our results show a viable solution to improve efficiency without changing the intrinsic quantum emitting efficiency of the material, and our design has potential applications in being incorporated with functional devices such as optical communications, integrated quantum memory, and quantum emission.