Automatic Monitor-Based Tuning of RF Silicon Photonic True-Time-Delay Beamforming Networks

Automatic group delay tuning of a lX4 RF Si-photonic asymmetric binary tree beamforming network structure is achieved with ring resonator drop port photodetectors providing electrical monitor information. The proposed tuning approach calibrates the group delay of an entire optical beamforming network (OBFN) that operates at 30GHz with 2GHz bandwidth. Compensation of process variations and thermal crosstalk is achieved with the 4 calibrated optical outputs displaying equal 41ps delay intervals.