On‐Chip Integrated Waveguide Amplifiers on Erbium‐Doped Thin‐Film Lithium Niobate on Insulator

Abstract On‐chip light amplification with integrated optical waveguide fabricated on erbium‐doped thin‐film lithium niobate on insulator (TFLNOI) is demonstrated using the photolithography‐assisted chemomechanical etching (PLACE) technique. A maximum internal net gain of 18 dB in the small‐signal‐gain regime is measured at the peak emission wavelength of 1530 nm for a waveguide length of 3.6 cm, indicating a differential gain per unit length of 5 dB cm −1 . This work paves the way to the monolithic integration of diverse active and passive photonic components on the TFLNOI platform.