New photonic asynchronous-transfer-mode switch with optical signal processing and code-division multiple access

We present the design of new photonic asynchronous-transfer-mode (ATM) swit ches that use optical code-division multiple access (CDMA) and strict optic al orthogonal codes (OOCs). All the peaks of cross-correlation functions an d all the sidelobes of any autocorrelation functions for a strict OOC are a lways limited to be a unit pulse-amplitude (i.e., 1 in the normalized case) for incoherent optical processing, regardless of whether an aperiodic or a periodic pulse sequence is input to optical CDMA decoders. Since the codin g and correlation of strict OOCs are performed in the optical domain by usi ng optical delay lines, the processing speed of the proposed photonic ATM s witch can be very high. This, in turn, can support real-time broadband comm unications. Owing to the correlation characteristics of strict OOCs, the pr oposed ATM switch can flexibly handle both equal-rate and variable-rate/mul tirate communication services without violating the cross-correlation and a utocorrelation constraints of 1 and with no change of optical CDMA encoders and decoders. This, in turn, can substantially improve the switch flexibil ity without increasing system complexity. (C) 1998 Society of Photo-Optical Instrumentation Engineers. [S0091-3286(98)00412-7].