Research on ultra-wideband and high saturation power uni-traveling carrier photodetectors (Invited)

Ultra-wideband uni-traveling carrier (UTC) photodetectors have broadband advantages over traditional PIN detectors, as only fast electrons are required to transport in UTC photodetectors. They will be one of the key optoelectronic devices in the sub-terahertz systems, such as 6G broadband wireless communications, terahertz imaging, ultra-wideband noise generators, etc. For the requirements of optoelectronic conversion in sub-terahertz frequency band, high-speed photo-generated carrier transport mechanics and inductive coplanar waveguide (CPW) structure were studied to improve the device bandwidth and saturation power of the photodetector. A dual-drift layer structure MUTC photodetector chip with bandwidth of 106 GHz, saturated output power of 7.3 dBm, and a CPW-optimized MUTC photodetector chip with bandwidth over 150 GHz were developed.