10 GBIT/S-DISPERSION OPTIMIZED TRANSMISSION AT 1.55-MU-M WAVELENGTH ON STANDARD SINGLE-MODE FIBER

The dispersion penalty increases with the spectral width of the modulated optical source. Pure AM leads to a two sided optical spectrum. Mixed FM and AM, produced by a directly modulated low-chirp laser diode, can lead to the partial suppression of one of those sidebands. Results of computer simulations are presented which yield lower dispersion penalties for mixed FM and AM compared to pure AM. A laser modulated at a bit rate of 10 Gbit/s, with a peak to peak frequency chirp of 3 GHz and an extinction ratio of 4:1 does operate in the desired regime. 180 km of fiber with a chromatic dispersion of 17 ps/km.nm lead to 2-dB dispersion penalty at those operating conditions.