Frequency multiplexing in millimeter-wave over fiber fronthaul transmission links with an InAs/InP quantum dash mode-locked laser

This study evaluates and compares four millimeter-wave (mmWave) radio-over-fiber (RoF) frequency multiplexing techniques considering InAs/InP quantum dash (QD) mode-locked lasers (MLLs) for optical carriers. The QD-MLL can generate multiple coherent optical carriers simultaneously with consistent frequency differences. Following heterodyne detection, the radio frequency linewidths of the QD-MLL can be minimized to 2.4 kHz. In this paper, four distinct RoF-based mmWave frequency multiplexing architectures are presented and compared experimentally. It is shown that the error vector magnitude of two 2 GBaud/s 16-QAM mmWave signals can reach as low as 7.1% after demultiplexing for all four techniques.