Transmission of a 20 Gb/s NRZ OOK signal throughout a 390 km fiber link and a cascade of 11 x 50 GHz filters and 9 x EDFAs

This paper presents a qualitative analysis of the impact caused by fiber propagation effects and by a cascade of optical filters, designed for 10 Gb/s NRZ OOK transmission, and optical amplifiers on a 20 Gb/s NRZ OOK optical signal traveling a 390 km fiber link. The choice for such bit rate and modulation format has been driven by the 50 GHz bandwidth of the filters (in the ITU DWDM grid) and by simplicity and low cost, respectively. The system, investigated experimentally and numerically, comprises 4 spans of standard fiber and a concatenation of 7 dispersion compensating modules, 4 wavelength selective switch reconfigurable optical add and drop multiplexers, 9 erbium-doped fiber amplifiers and 1 WDM-DEMUX (> 75 GHz bandwidth). We demonstrate the feasibility of such bit rate upgrade in a cost-effective network planning strategy, which may be more adequate for regions where the demand for bandwidth do not require a jump to higher capacities (i.e. 40 and 100 Gb/s), thus allowing for reusing the 10 Gb/s installed infrastructure