Abstract

Within a large wavelength-division multiplexed (WDM) network, data from N independent WDM channels arriving at a single node may need to be time-division multiplexed (TDM) onto a single signal at a given wavelength and then transmitted across the network.^1,2 Such a scenario is advantageous when there is limited available system bandwidth imposed by, for example, system nonlinearities or technological limitations on the number of available wavelengths.³ The WDM-to-TDM conversion process is very attractive, and to avoid any optoelectronic speed bottlenecks, the conversion process should be alloptical. We demonstrate an error-free and nearly penalty-free all-optical WDM-to-TDM node that incorporates the useful functions of: (1) data format transparency; (2) extinction ratio enhancement; (3) time multiplexing; and (4) wavelength shifting, to convert two WDM channels into one high-speed TDM signal. The advantages in our approach include: (1) the conversion process is all-optical and transparent to the NRZ and RZ data formats; (2) the extinction ratio enhancement module results in nearly penalty-free performance; (3) the data polarity between the input WDM channels and the output TDM signal is preserved; and (4) the WDM-to-TDM conversion can be realized over a very wide wavelength range (~40 nm). We demonstrate this node by converting two 1-Gbit/s NRZ WDM channels at 1552 and 1548 nm into one 20-Gbit/s TDM signal at 1558-nm, while incurring only a 0.2-dB power penalty. This node may be a key building block for fully functional, dynamically reconfigurable WDM networks, which require transparency and cascadability.

© 1996 Optical Society of America