A Photonic-Assisted Transmitter Integrated With a High-Power Traveling Wave Photodetector and a Yagi Antenna on Silicon-on-Insulator Substrate

Abstract

A mm-wave photonic-assisted transmitter chip composed of a high-power distributed traveling wave photodetector (TWPD), a compact Yagi antenna, and a bias circuitry network is demonstrated on a silicon-on-insulator (SOI) substrate. By aperiodically loading four Ge/Si photodetector (PD) units on the traveling-wave electrode, the TWPD achieves a bandwidth of 42 GHz and a saturation RF output power of 1.4 dBm at the target frequency of 35 GHz. The RF output of the TWPD then directly drives the Yagi antenna monolithically integrated on the same chip. To enhance the RF power delivery efficiency from the TWPD to the antenna, the geometry of the Yagi antenna is optimized so that its impedance is conjugately matched to that of the TWPD. The optimized antenna presents a gain of 3 dBi at 35 GHz along the endfire direction, while its half-power beamwidths are 105° at both E- and H-planes. The transmitter chip provides high effective isotropic radiated powers (EIRPs) of 1.8/3.2 dBm at 35/32 GHz. Furthermore, it successfully transmits a 35 GHz wireless signal encoded with an 8 Gb/s data stream in the nonreturn-to-zero (NRZ) on-off-keying format.