Photonic Beamforming Incorporating Ring Resonator Based on Silicon-on-Insulator Waveguide Technology

Millimeter-wave band opens new opportunities for ultra-high data rates and dense connectivity in forthcoming 5G and 6G wireless cellular networks. However, the major challenge is the significant propagation loss experienced by millimeter-wave. The beneficial solution to overcome this is to exploit beamforming with multiple antennas. In this paper, we propose a silicon-on-insulator waveguide technology based 1 × 2 integrated photonic beamformer for 28 GHz signal. The true time delay line is realized by utilizing micro-ring resonator. Ring resonator of 30 µm radius designed using single mode rib waveguide is considered. Firstly, the dimensions of waveguide to maintain single mode operation are estimated. Next, mathematical analysis and design of the beamforming structure are presented. True time delay of 12.46 ps is achieved, corresponding to a phase difference of 0.708π and beam pointing angle of 45.06˚. Finally, thermo-optic tuning is performed to incorporate continuous tunability feature into the delay device. By adjusting the power coupling coefficient of coupler, the designed beamformer can provide continuous tuning range of 0˚ to 60˚.