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

• Published in: Journal of lightwave technology Vol. 40; no. 12; pp. 3602 - 3613
• Main Authors: Plabst, Daniel, Prinz, Tobias, Wiegart, Thomas, Rahman, Talha, Stojanovic, Nebojsa, Calabro, Stefano, Hanik, Norbert, Kramer, Gerhard
• Format: Journal Article
• Language: English
• Published: New York IEEE 15.06.2022; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Amplitude shift keying; capacity; Channels; Codes; Complexity; direct detection; Fiber optics; intensity modulation; Interference; Mathematical models; Optical fiber communication; Optical fiber dispersion; Optical transmitters; Oversampling; quadrature amplitude modulation; Receivers; Time-domain analysis
• ISSN: 0733-8724; 1558-2213
• DOI: 10.1109/JLT.2022.3149574

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