We examine pulse amplitude modulation (PAM) for intensity modulation and direct detection systems. Using a straight-forward, mixed noise model, we optimize the constellations with an autoencoder-based neural network (NN), an improve required signal-to-noise ratio of 4 dB for amplified spontaneous emission (ASE)-limited PAM4 and PAM8, without increasing system complexity. Performance can also be improved in O-band wavelength division multiplexing system with semiconductor optical amplifier amplification and chromatic dispersion. We show via simulation that for such a system operating at 53 Gbaud, we can extend the reach of PAM4 by 10-25 km with an optimized constellation and a NN decoder. We present an experimental validation of 4 dB improvement of an ASE-limited PAM4 at 60 Gbaud using an optimized constellation and a NN decoder.
@article{arxiv.2402.04395,
title = {Auto-Encoder Optimized PAM IM/DD Transceivers for Amplified Fiber Links},
author = {Amir Omidi and Mai Banawan and Erwan Weckenmann and Benoit Paquin and Alireza Geravand and Zibo Zheng and Wei Shi and Ming Zeng and Leslie A. Rusch},
journal= {arXiv preprint arXiv:2402.04395},
year = {2024}
}