Silicon photonic coherent adder for communication and sensing with time-multiplexed control feedback

Time-multiplexed control of a reconfigurable silicon photonic coherent adder is demonstrated by means of monolithically integrated CMOS electronics. Time-multiplexing is used to interrogate integrated photodetectors and drive thermal actuators with few electrical signals, realizing accurate compensation and locking of mutual phase drifts of the input signals to be combined. The optical circuit functionality is then demonstrated both with a transmission experiment, where a 25 Gbps modulated signal is reconstructed at the chip output, and in a sensing scenario, where the chip is used to assess the phase difference between the input light beams.