Fiber delay lines optical buffer for ATM photonic switching applications

An optical buffer shift register based on a set of fiber delay lines is presented, with the goal of providing cell storage and queuing in asynchronous transfer mode (ATM) photonic switches. The concept of multiwavelength cell buffering is adopted, to realize a shared buffer with a storage capacity equivalent to a set of shift registers. Since only one wavelength-encoded cell must enter one delay line at each time slot, contention resolution is necessary to determine the queuing order between the incoming cells. The use of optical fibers as delay lines and semiconductor optical amplifiers as gates associated with passive splitters to realize buffering and time-switching has been demonstrated. An experimental setup has been implemented at 600 Mb/s and operates without guard bands between packets. The low penalty observed shows that system synchronization and reliability are good.<>