Automated Routing and Control of Silicon Photonic Switch Fabrics

Automatic reconfiguration and feedback controlled routing is demonstrated in an
$8 \times 8$
silicon photonic switch fabric based on Mach–Zehnder interferometers. The use of noninvasive contactless integrated photonic probes (CLIPPs) enables real-time monitoring of the state of each switching element individually. Local monitoring provides direct information on the routing path, allowing an easy sequential tuning and feedback controlled stabilization of the individual switching elements, thus making the switch fabric robust against thermal crosstalk, even in the absence of a cooling system for the silicon chip. Up to 24 CLIPPs are interrogated by a multichannel integrated ASIC wire bonded to the photonic chip. Optical routing is demonstrated on simultaneous WDM input signals that are labeled directly on-chip by suitable pilot tones without affecting the quality of the signals. Neither preliminary circuit calibration nor lookup tables are required, being the proposed control scheme inherently insensible to channels power fluctuations.