Optical cross-connection configuration based on FDM technologies

The configuration of an optical frequency division multiplexing (FDM) cross-connect system that uses passive frequency-channel selection filters and tunable laser diodes as frequency switches and transmitters is described. The three system configurations, based on FDM, space division multiplexing (SDM), and time division multiplexing (TDM) technologies, are compared from the viewpoint of power consumption. The comparison suggests that the FDM cross-connect system configuration will yield practical systems. Small signal analysis of a distributed Bragg reflector laser diode (DBR-LD) as a tunable and switching laser is used to investigate its available switching time and operation conditions. The analysis results are useful in determining the allowable number of channels and the number of guard bits inserted between STM frames. Bit error free operation is demonstrated by using two laser diodes per channel. The feasibility of the FDM system configuration is experimentally clarified in a 156-Mb/s cross-connection unit