Efficient Self‐Amplification in Monolithically Integrated Laser on Er/Yb Co‐Doped Lithium Niobate on Insulator

Light sources constitute an indispensable component in photonic integrated circuits (PICs), with lithium niobate on insulator (LNOI) emerging as an ideal platform for PICs. Although rare‐earth ion doping has been employed to introduce optical gain, achieving high output power and high slope efficiency simultaneously remains challenging in micron‐scale lasers. Here, a high‐performance, monolithically integrated Er/Yb co‐doped LNOI laser that leverages a cascaded microring‐amplifier architecture is demonstrated. By integrating a spiral waveguide amplifier, the device achieves a significant signal enhancement of 28.21 dB over the sole microring laser. Optimized through a bidirectional pumping scheme at 980 and 1480 nm, the laser harnesses strengthened ytterbium to erbium ions energy transfer to reach a maximum output power of 3.94 µW and a slope efficiency of 0.64%. This work establishes a practical and robust approach for realizing high‐performance on‐chip lasers, highlighting the strategic advantage of self‐amplifying designs for future communication and signal‐processing systems.