Sub-Terahertz Transceiver Module Integrating Uni-Traveling-Carrier Photodiode, Schottky Barrier Diode, and Planar Circulator Circuit

A compact sub-terahertz transceiver module integrating a uni-traveling-carrier photodiode, a Schottky barrier diode, and a planar circulator circuit has been developed. A 180-degree rat-race hybrid circuit fabricated on a quartz substrate is employed as the circulator. All the components are assembled in a compact rectangular-waveguide-output package for operation in the J-band. The frequency dependence of the detection sensitivity of the transceiver module showed clear resonant behavior at around 270 GHz while the output power showed no distinct resonance. The insertion loss of the circulator for the input and output signals at 270 GHz were estimated to be 4.6 dB and 11.4 dB, respectively. The isolation between the output port and the SBD port of the circulator was evaluated to be 14.3 dB at 270 GHz, indicating that the fabricated module functioned properly as a transceiver. The linearity of the output power and the input sensitivity of the transceiver were also confirmed to be very good. This is the first demonstration of a photonic mm-wave transceiver module for continuous waves operating at around 300 GHz.