Hai-Han Lu, a life distinguished professor in the Department of Electro-Optical Engineering at Taipei Tech, led a cross-campus research team to improve current 5G technical limitations by adopting single optical carrier modulation. Their research findings were published in "Communications Engineering", an internationally renowned journal from the “Nature” portfolio. It is the first paper from Taiwan to be published in the journal, greatly enhancing the country’s international visibility on the topics of 5G technology and free-space optical (FSO) communication systems. 

Prof. Lu is currently a fellow of the International Society for Optics and Photonics (SPIE) and the Institution of Engineering and Technology (IET). He has won the Outstanding Engineering Professor Award from the Chinese Institute of Engineers and the Sun Yat-sen Academic Award (Natural Science) from the Sun Yat-sen Academic and Cultural Foundation. He has also been awarded the Taipei Tech Outstanding Research Award for nine consecutive years.

Prof. Lu indicated that the current 5G technology mostly utilizes multi-optical carrier modulation. In order to support the 5G wireless transmission of high-frequency signals, a large number of base stations are required to meet the demand, and the signal interference is also a problem to be solved. “The multi-optical carrier signals are just like a crowded MRT train,” said Lu, “the signals interfere with each other, resulting in the degradation of transmission performance." 

The research team proposed an innovative solution. By using the 40-kilometer single-mode fiber to transmit a single optical carrier, and generating multi-optical carrier modulation through the Mach-Zehnder modulator (MZM) optoelectronic oscillator (OEO), it can simultaneously transmit a large number of signals, effectively suppressing RF power fading caused by fiber dispersion and interference due to optical beating from multiple optical carriers.

Comparing to the current 5G fiber broadband system, the combined fiber/FSO communication system at MMW/sub-THz frequencies that the research team proposed has demonstrated ultra-high transmission rate, long-haul transmission distance and excellent transmission performance, providing strong technical support for the development of various innovative applications in the 5G field. Prof.Lu further noted that the system can also be broadly used in high-speed autonomous vehicles, intelligent drone patrols, smart IoT, smart healthcare, and industrial automation.

Paper publication link: https://www.nature.com/articles/s44172-023-00068-1