Time alignment of optical cells with arbitrary message payloads

Summary form only given. Ultrafast (100 Gbit/s) optical time-division multiplexed (OTDM) signals must be transmitted exclusively in the optical domain due to the speed limitation of present optoelectronic and digital circuitry. Cell-based switch nodes must perform alignment, routing and contention resolution functions directly on the optical data in order to remain transparent to the ultrafast data signal. The time synchronization function is required at the front end of a transparent optical switch to align incoming cells with the switch node timing and prevent cell jitter accumulation. The alignment method described here employs a fiber-optic binary-weighted delay line (BDL) that is electronically configured by a cell header receiver referred to as the Optical Cell Header Interface Subsystem (OCHIS). Results obtained using a prototype three-stage BDL with 1-ns resolution are presented.