Signal-to-noise ratio of modulated sources of ASE transmitted over dispersive fiber

We investigate, both theoretically and experimentally, the signal-to-noise ratio (SNR) of modulated amplified spontaneous emission (ASE) transmitted over dispersive fiber. We observe two significant effects; firstly, the signal-to-excess-noise ratio (SNR/sub ex/) varies across the pulse reaching its maximum value near the peak of the detected signal; and secondly, this maximum value decreases with increasing fiber dispersion-induced pulse broadening. Accurate calculation of transmission performance of high bit-rate optical communication systems employing ASE sources, such as spectrum slicing, requires inclusion of these effects.