The unprecedented demand for optical network capacity has fueled the development of long-haul optical network systems which employ wavelength-division multiplexing(WDM) to achieve tremendous capacities. Such systems transport tens to hundreds of wavelengths per fiber ,with each wavelength modulated at 10 Gb /s or more [1].The switching burden in such systems has been laid almost entirely on electronics. In every switching node, optical signals are converted to electrical signals (O-E conversion), buffered electronically, and subsequently forwarded to their next hop after being converted to optical form again (E-O conversion).