Time‐Multiplexed Control of Programmable Silicon Photonic Circuits Enabled by Monolithic CMOS Electronics

Programmable photonic circuits require an electronic control layer to configure and stabilize the optical functionality at run‐time. Such control action is normally implemented by supervising the status of the circuit with integrated light monitors and by providing feedback signals to integrated actuators. This paper demonstrates that the control action can be effectively performed with electrical signals that are time‐multiplexed directly on the photonic chip. To this aim, the necessary electronic functionalities are monolithically integrated in a conventional 220 nm silicon photonics platform with no changes to the standard fabrication process. By exploiting a non‐conventional structure to implement metal‐oxide–semiconductor field‐effect transistors, an electronic controller is co‐designed into a programmable photonic circuit to enable a time‐multiplexed readout of integrated photodetectors and sequential activation of thermal phase shifters with on‐chip electronic memory. The accuracy of the time‐multiplexed control, achieved on a time scale of less than 10 ms, is demonstrated by penalty‐free routing of 10 Gbit s−1 modulated signals. This approach can be straightforwardly applied to large‐scale photonic chips to reduce the number of required electrical input/output connections. Non‐conventional CMOS transistors are exploited to co‐integrate an electronic controller into a programmable silicon photonic circuit. The electronics enable time‐multiplexed control of the on‐chip optical devices by sequentially reading the integrated photodetectors and driving actuators. The approach allows for a reduction in the number of electrical I/O connections required to operate large‐scale photonic chips.