Integration of traveling-wave photodetector and coplanar-fed log-periodic antenna for terahertz source generation

In this paper, integration of high-power travelling-wave photodetector (TWPD) and broadband log-periodic antenna with coplanar waveguide (CPW) fed is proposed and designed for terahertz (THz) generation. In this integrated device, THz signal is generated and radiated by optical signals coming from telecommunication lasers in the range of 1550-nm. Design and analysis of the edge illuminated PIN-type TWPD up to 1 THz are studied and then phase velocity and loss of the device are compared with the measured results. Also, two bandwidth limitation factors of the TWPD including optical and microwave phase velocity mismatch as well as carrier drift velocity are discussed. In addition, the structure of conventional log-periodic antenna with coplanar strip (CS) fed is modified and integrated with the CPW output of the TWPD. Design and analysis of this broadband complementary CPW-fed antenna are presented in the paper.