On-chip coherent beam combination of waveguide amplifiers on Er³⁺-doped thin film lithium niobate

We demonstrate on-chip coherent beam combination of two waveguide amplifiers on Er³⁺-doped thin film lithium niobate (Er:TFLN) platform. Our device is built based on an electro-optic modulator fabricated on Er:TFLN. The output power of the coherently combined amplifiers is measured as high as 12.9 mW, surpassing that of previous single waveguide amplifiers based on an Er³⁺-doped thin film lithium niobate platform.