Efficient erbium-doped thin-film lithium niobate waveguide amplifiers

Lithium niobate on insulator (LNOI) is an emerging photonic platform with great promise for use in future optical communications, nonlinear optics, and microwave photonics. An important integrated building block, active waveguide amplifiers, however, are still missing the LNOI platform. Here, we report efficient compact amplifier based erbium-doped waveguides, achieved using a sequence of crystal growth, ion slicing, lithography-based fabrication. Using 5 mm long waveguide, demonstrate on-chip net gain > 5 d mathvariant="normal">B 1530 nm signal light relatively low pump power 21 mW at 980 nm. The amplifiers could become fundamental element lithium circuits.