Achievable Rates for Short-Reach Fiber-Optic Channels With Direct Detection

Spectrally efficient communication is studied for short-reach fiber-optic links with chromatic dispersion (CD) and receivers that employ direction-detection oversampling. Achievable rates symbol error probabilities are computed by using auxiliary channels account memory in the sampled strings. Real-alphabet bipolar complex-alphabet symmetric modulations shown to achieve significant energy gains over classic intensity modulation. Moreover, frequency-domain raised-cosine (FD-RC) pulses outperform time-domain RC (TD-RC) terms of spectral efficiency two scenarios. First, if one shares spectrum other users then inter-channel interference significantly reduces TD-RC rates. Second, there a transmit filter avoid detection complexity FD-RC similar but achieves higher