ALL-OPTICAL DATA FORMAT CONVERSIONS AND RECONVERSIONS BETWEEN THE WAVELENGTH AND TIME DOMAINS FOR DYNAMICALLY RECONFIGURABLE WDM NETWORKS

We demonstrate all-optical error-free 2 Gb/s data format conversions a nd reconversions between the wavelength and time domains. Conversion b etween these two domains is accomplished by performing single-stage TD M-to-WDM and WDM-to-TDM conversions, We also perform the function of c onverting back all-optically to the original domain by performing both WDM-to-TDM-to-WDM and TDM-to-WDM-to-TDM reconversions. All conversion s and reconversions are realized by using the cross gain compression m echanism inherent in semiconductor optical amplifiers (SOA's). We firs t demonstrate our TDM-to-WDM converter by simultaneously time demultip lexing and wavelength shifting a four-channel 2 Gb/s TDM data stream i nto four 500 Mb/s WDM channels. Moreover, we extend this single-stage approach by demonstrating a two-stage TDM-to-WDM converter consisting of two cascaded single-stage TDM-to-WDM modules. This two-stage conver ter selectively time demultiplexes and wavelength shifts a four-channe l 2 Gb/s TDM data stream into two 500 Mb/s WDM channels after the seco nd stage, Furthermore, we demonstrate a WDM-to-TDM converter by simult aneously time multiplexing and wavelength shifting the data from two 1 Gb/s WDM channels into one 2 Gb/s TDM signal. Finally, we demonstrate reconversion between the wavelength and time domains for two channels by performing both WDM-to-TDM-to-WDM and then TDM-to-WDM-to-TDM recon versions. In order to demonstrate system robustness, we use 50 km of f iber and three EDFA's between the conversion and reconversion stages, We show that reconverting back to the TDM data format requires an inte rstage WDM channel wavelength range less than similar to 4 nm, due to the power penalty induced by the interstage relative phase shift betwe en the channels. This constraint limits the operation of the TDM-to-FV DM-to-TDM reconverter to data rates up to 10 Gb/s and interstage dista nces to similar to 100 km. All demonstrated conversion and reconversio n processes are accomplished with low power penalties. These conversio n and reconversion schemes could be useful in WDM switching nodes and mag serve as keg building blocks for all-optical WDM networks.