Non-invasive monitoring and control in silicon photonics by CMOS integrated electronics

As photonics moves from the single-device level toward large-scale, integrated, and complex systems on a chip, monitoring, control, and stabilization of the components become critical. We need to monitor a circuit non-invasively and apply a simple, fast, and robust feedback control. Here, we show non-invasive monitoring and feedback control of high-quality-factor silicon (Si) photonic resonators assisted by a transparent detector that is directly integrated inside the cavity. Control operations are entirely managed by a CMOS microelectronic circuit that is bridged to the Si photonic chip and hosts many parallel electronic readout channels. Advanced functionalities, such as wavelength tuning, locking, labeling, and swapping, are demonstrated. The non-invasive nature of the transparent monitor and the scalability of the CMOS readout system offer a viable solution for the control of arbitrarily reconfigurable photonic integrated circuits aggregating many components on a single chip.