Signal-to-noise ratio of spectrum-sliced incoherent light sources including optical modulation effects

We have derived the beat-noise-limited signal-to-noise ratio (SNR) of spectrum-sliced incoherent light sources, including optical modulation effects. SNR changes significantly in time depending on the received optical pulse shape and the receiver electrical filter. Thus, the optimum decision point at the optical receiver may be much different from the peak signal point and the sampled SNR may be different from the continuous-wave SNR. To obtain high SNR, small rise and fall times are required and the non-return-to-zero modulation format is recommended.