Wave division multiplexing based optical switch

Abstract

An optical switch utilizing WDM or DWDM techniques for use in both WAN and LAN environments. Each input to the switch is assigned a separate wavelength via a tunable transmitter. The output of the transmitters are input to a star coupler which combines all the optical signals into a single optical output signal. This signal is input to an optical demultiplexor which functions to split the incoming optical signal into a plurality of separate wavelengths with each wavelength steered to a particular output port. The output of each port, corresponding to a particular wavelength, is then converted into an electrical signal by a receiver. Unicast, broadcast and multicast calls are supported. A plurality of unicast connections can be established simultaneously by assigning each tunable transmitter a different wavelength such that all wavelengths are mutually exclusive with each other. In a broadcast connection, the source node transmits and all output ports receive the optical signal on the particular wavelength assigned to that port. The rest of the input ports are placed in an idle state. The output of each port is input to a multiplexor along with an output of the optical demux dedicated to broadcast traffic. A controller switches the multiplexors to output the broadcast signal such that all receivers output the same signal. Multicast traffic is handled similarly except that only selected multiplexors are switched. The remaining multiplexors carry unicast traffic as normal. As a result, the output ports of the members of the multicast group all output the same signal.