Abstract
Probabilistic shaping for intensity modulation and direct detection (IM/DD)
links is discussed and a peak power constraint determined by the limited
modulation extinction ratio (ER) of optical modulators is introduced. The input
distribution of 4-ary unipolar pulse amplitude modulation (PAM) symbols is
optimized for short-reach transmission links without optical amplification nor
in-line dispersion compensation. The resulting distribution is symmetric around
its mean allowing to use probabilistic amplitude shaping (PAS) to generate
symbols that are protected by forward error correction (FEC) and that have the
optimal input distribution. The numerical analysis is confirmed experimentally
for both an additive white Gaussian noise (AWGN) channel and a fiber channel,
showing gains in transmission reach and transmission rate, as well as rate
adaptability.
Original language | English |
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Journal | Journal of Lightwave Technology |
Volume | 39 |
Issue number | 2 |
Pages (from-to) | 400-405 |
ISSN | 0733-8724 |
DOIs | |
Publication status | Published - 2020 |
Keywords
- Probabilistic Shaping
- 4-PAM
- Intensity Modulation
- Direct Detection
- Peak Power Constraint