Saturation effects in heterogeneously integrated high-speed photodiodes on thin-film lithium niobate

We report on modified uni-traveling carrier photo- diodes (MUTC PDs) on thin-film lithium niobate (TFLN) waveguides with a 1-dB compression photocurrent of 9 mA and -1.9 dBm radio frequency (RF) output power at 48 GHz. The extracted effective (space-charge) resistance is 434 Ω, and optical simulations suggest that performance at high photocurrents can be further enhanced by optimizing the TFLN waveguide width.