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Centre for Advanced Photonics and Electronics

CAPE Lecture – Prof. Shien-Kuei Peter Liaw: Free-space optic WDM bidirectional transmission: Design and Evaluation

In this talk, high-speed free space optics communication (FSO) technologies will be reviewed and introduced. We design and demonstrate two proposed FSO schemes. The first scheme is a bi-directional, short-range and free-space optical (FSO) communication with 2x4x10 Gb/s capacity in wavelength division multiplexing (WDM) channels for short-distance transmission. Compared to the back-to-back link and uni-directional transmission system, the measured power penalties for bi-directional, four-channel WDM FSO communication are less than 0.8 dB and 0.2 dB, respectively. The second scheme is the hybrid optical fiber and FSO link for outdoor environment, such as cross bridge or inter-building system. In case that the bridge breaks, the transmission path can be switched from fiber link to FSO link to ensure the connectivity of data link. In both cases, the single-mode-fiber (SMF) components are used in the optical terminals for both optical transmission and receiving functions. The environmental and infrastructure factors including window glasses, air turbulence and rainfall that influence the case will also be addressed. The air turbulence induces extra transmission loss and instability in the received power. We found that raindrops are the most influential environmental factor. The bit error rate (BER) test shows that raindrops seriously increase the BER that may interrupt the transmission instantaneously. After appropriate performance improvement, the proposed transmission structures show potential applications for outdoor transmission under various natural weather conditions.



Prof. Shien-Kuei Peter Liaw received double doctorate degrees in photonics engineering from National Chiao-Tung University and mechanical engineering from National Taiwan University. He joined the Chunghua Telecommunication, Taiwan, 1993. Since then, he has been working on optical communication and fiber based technologies. Prof. Liaw has worked at the department of Electronic Engineering, National Taiwan University of Science and Technology (NTUST) since 2000. He is the Director of the Optoelectronics Research Center, Director of the Technology Transfer Center, and Vice Chairman of the Electronic Engineering department of NTUST. In addition, he was an academic visitor at the University of Oxford for three months in 2011 and owns 40 patents in the U.S., Taiwan and China, authored or co-authored more than 250 journal articles and international conference papers. He has been actively contributing to numerous conferences as a program chair, as an international advisory committee member, a steering committee member, a keynote speaker and an invited speaker. He serves as an Associate Editor for Fiber and Integrated Optics (a SCI Journal). Currently, Dr. Liaw is a Distinguished Professor and Vice Dean of the College of Electrical and Computer Engineering, NTUST, and the president of the Optical Society (OSA) Taiwan Section and Secretary-General of the Taiwan Photonic Society. His research interests are in fiber sensing, optical communication and reliability testing.