On-Chip Time-Multiplexed Electronic Control of a Silicon Photonic Coherent Adder for Communication and Sensing

Abstract: The growing complexity of reconfigurable photonic circuits, made possible by the established maturity of silicon photonic foundries, demands efficient strategies to monitor and actively control the optical functionality at runtime. In this work, we show that both the readout of integrated sensors and the driving of actuators can be performed with a time-multiplexed addressing scheme, that drastically reduces the number of electrical connections required to interface the chip to the external hardware. This approach is achieved by monolithically integrating the electronic circuits needed to serialize/deserialize the feedback action directly on the photonic chip. We experimentally validate the proposed strategy with a silicon photonic coherent adder, showing that such time-multiplexed control does not introduce any penalty in the optical functionality. The circuit operation is then validated in a joint communication and sensing scenario, where the coherent adder is used to simultaneously receive a 25 Gbps high-speed transmission and to measure the phase difference between the input light beams.