An optical gateway to convert four-level pulse amplitude modulation to quadrature phase shift keying modulation format having shaping gain was proposed for flexible intensity to phase mapping which exploits non-uniform phase noise. The power consumption of the optical modulation format conversion can save by making a DNN-based decision on the receiver side for the generated QPSK signal with non-uniform phase noise. A proof-of-principle experiment has shown that an optically geometric constellation shaped QPSK modulated signals generated from regular PAM4 signals with Gaussian-distributed noise. The shaped QPSK signal shows BER and generalized mutual information improvement by 1dB gain through the use of digital neural network signal recovery.
@article{arxiv.2102.13474,
title = {DNN-assisted optical geometric constellation shaped PSK modulation for PAM4-to-QPSK format conversion gateway node},
author = {Takahiro Kodama and Toshiaki Koike-Akino and David S. Millar and Keisuke Kojima and Kieran Parsons},
journal= {arXiv preprint arXiv:2102.13474},
year = {2022}
}