Development of Microwave and Millimeter-Wave Traveling-Wave Electro-Optical Devices Using Substrate Integrated Circuit Concept

This paper begins with an overview of conventional microwave and millimetre-wave (mmW) traveling-wave (TW) electro-optical devices with emphasis on mmW characteristics. In particular, TW electrodes in the form of microstrip line (MS) and coplanar waveguide (CPW) are discussed with respect to guided-wave properties (loss, transmission, impedance) as well as electrical/optical field interactions. Then, the concept of substrate integrated circuits (SICs) is presented for optoelectronic device design. A number of TW electro-optical devices are examined, which include waveguide photodetectors (WGPDs), TW photodetectors (TWPDs) and modulators. It is anticipated that those mmW waveguides exhibiting a high transmission loss can effectively be replaced by the new substrate integrated waveguide (SIW) concept. A comparison of basic properties between MS, CPW and SIW structures is presented. It is found that the proposed SIC´s including substrate non-radiative dielectric (SINRD) guide present very promising candidates for designing low-loss and high-efficient TW electro-optical devices for in mmW photonics and broadband radio-over-fibre applications.