Heterogeneous integration of uni-travelling-carrier photodiodes using micro-transfer-printing on a silicon-nitride platform

High-speed photodiodes often compromise responsivity in exchange for a reduced footprint. However, using waveguide photodiodes circumvents this limitation [1] . We combine uni-travelling-carrier photodiodes (UTC PDs) on a silicon nitride (SiN) photonic platform to achieve both high responsivity and high speed detectors. The SiN-platform has excellent properties such as low-loss waveguides and does not suffer from two-foton absorption at high optical power. A high responsivity is obtained through evanescent coupling of waveguide UTC photodiodes to SiN waveguides while still maintaining a small footprint.