  With the advantages of large electro-optical coefficient, wide transparency
window, and strong optical confinement, thin-film lithium niobate (TFLN)
technique has enabled the development of various high-performance
optoelectronics devices, ranging from the ultra-wideband electro-optic
modulators to the high-efficient quantum sources. However, the TFLN platform
does not natively promise lasers and photodiodes. This study presents an
InP/InGaAs modified uni-traveling carrier (MUTC) photodiodes heterogeneously
integrated on the TFLN platform with a record-high 3-dB bandwidth of 110 GHz
and a responsivity of 0.4 A/W at a 1550-nm wavelength. It is implemented on a
wafer-level TFLN-InP heterogeneous integration platform and is suitable for the
large-scale, multi-function, and high-performance TFLN photonic integrated
circuits.
