Bulletin No. 2, 2024

It was boredom that drove Professor Tsang Hon-ki into his current academic field. While an undergraduate student in engineering at the University of Cambridge in the 1980s, the current Dean of Engineering at CUHK spent a few months interning at a telecommunications company. There he quickly realised that his passion was not in writing computer code: “I was bored out of my mind,” he says. “I was just facing the same code and then debugging the code and doing the same thing there, and I thought ‘after I graduate, I do not want to enter that as a profession’.” Having also worked at that company’s optical fibre communications lab, he found himself more fascinated by the fledgling optics industry and its possibilities. This sparked a lifelong interest in optics that has culminated in his leadership of a startup dedicated to the design of silicon photonic chips. Most silicon chips these days contain many electrical signals which enable information to be transmitted. However, as such signals also generate heat on the side, this creates problems: “If you go beyond around five or six gigahertz, which is the switching speed of a notebook computer, the electric wires will generate so much heat that the chip would become unusable,” says Professor Tsang. On the other hand, light presents no such issues, as optical signals can be switched very quickly: “100 Giga-baud [a speed unit] is no problem, and you can transmit that for kilometres because that's the advantage of using light. So you can go at whatever One of the components of Professor Tsang’s research in silicon photonics 23