Non-invasive light sensor with enhanced sensitivity for photonic integrated circuits

Complex photonic architectures integrated into a single silicon chip require real-time control to keep each device at the desired working point. With this aim, non-invasive optical sensors are an effective solution, allowing to monitor the light inside optical waveguides without penalties in the photonic functionality. Here, the working principle of the CLIPP sensor and its electronic readout are presented and discussed in order to understand how to improve the performance and scale down the size. An improved version of the CLIPP is then presented, featuring a 10-fold improvement in the sensitivity and reaching unprecedented performance for transparent detectors, while also maintaining a small area occupation. Finally, a differential CLIPP readout scheme is discussed, which allows to mitigate the effect of common-mode disturbances.