Review of JLT Optical Communication paper, January 2022. Part 1

Optical fiber communication  
Irene Estebanez et al. from The Institute of Physics and Complex Systems in Spain used the extreme Learning Machine (ELM) algorithm to recover the received data of the optical fiber transmission system, as shown in Figure 1.  Experimental research is carried out in 100km optical fiber transmission system using 56GBand four-level pulse amplitude modulation (PAM-4) and direct detection.  Researchers introduced delay reserve algorithm (TDRC) as a comparison scheme, and proved that adopting ELM algorithm can further simplify system configuration, eliminate the limited influence of computing speed caused by time delay, and have nearly the same transceiving performance as adopting TDRC scheme [1].  The scheme supports error-free decoding when the optical signal-to-noise ratio (OSNR) is greater than 31dB, and has better error performance than the KK receiving scheme implemented by offline digital Signal processing (DSP).