Half-cycle modulation for VCSEL based 6-Gbaud 4-QAM transmission over 1 km multimode fibre link

摘要

A subcarrier multiplexing system with the subcarrier frequency at half the baud rate to improve the spectral efficiency is demonstrated. A 12 Gbit/s 4-QAM signal in 9GHz bandwidth was successfully transmitted over a 1 km OM4 MMF 850 nm VCSEL without any equalisation method. The 1.5 dB power penalty was improved compared to an OOK signal at the same data rate.