Reconfigurable CROW delay lines on a silicon platform

The potential of coupled resonator optical waveguides (CROWs) as integrated reconfigurable delay lines has been recently demonstrated in a glass-based device by continuously controlling the delay of optical data streams over several bit lengths. Although the exploitation of a medium index contrast glass waveguide leads to low insertion losses, allowing large absolute delays, it poses a hard limit on the maximum bandwidth of the device. The leap toward a high index contrast silicon platform is therefore mandatory for the processing of signals at high bit-rates (> 40 Gbit/s). The higher the bit rate, the lower is the required absolute delay (the fractional delay being equal) - this compensates for the higher losses of silicon waveguides while preserving the performance of the reconfigurable CROW in terms of storage efficiency and easy management of the delay. In this paper, the authors present a preliminary characterization of a reconfigurable CROW delay line realized in silicon-on-insulator (SOI) with thermooptic control of the delay.