Control architecture for high capacity multistage photonic switch circuits

A layered, digital control architecture is proposed and demonstrated for relaxed-tolerance multistage photonic circuits. Preallocated optical paths and precalibrated switches are used in a hierarchical control scheme to anticipate and equalize power fluctuations from multiple input paths. Fast reconfigurability is facilitated, which ensures predefined optical powers at the switch stage outputs without incurring excess time delay or power transients. Experimental validation has led to the development of a dual stage switch router with three input nodes each transmitting four 10 Gbit/s wavelength multiplexed payloads. Low penalty power equalization is observed after both a first and a second stage switch and is extendable to 10??10 Gbit/s operation. We show that the output power is indeed set to within 0.5 dB at 0 dBm for an input power dynamic range of more than 20 dB. The combination of selfcalibration and modular control demonstrated in a two stage switch topology is believed to be scalable to more sophisticated multistage networks. As the concept does not require delay lines, it is believed that it will have advantages in facilitating the integration of controlled photonic circuits.