Error-free continuously-tunable delay at 10 Gbit/s in a reconfigurable on-chip delay-line

A coupled-resonator optical waveguide (CROW) consisting of a chain of directly coupled ring-resonators (RRs) fabricated in 4.5%-indexcontrast silicon oxynitride technology is employed to control the delay of optical pulses with continuity and over several bit-slots. The moderate deterioration of the signal quality versus the delay is demonstrated by the observation of error-free transmission (BER < 10-9) at 10 Gbit/s for fractional delays of up to 3 bits, with fractional losses below 1 dB per bit-delay. The high storage efficiency of the device, exceeding 0.5 bit/RR, enables an easy management of the delay and the reduction of the footprint down to 7 mm2. The presented reconfiguration scheme is hitless with respect to data transmission, since the CROW delay can be tuned without halting the data flow, while preserving the signal quality.