Someone once asked an absurd question: When will the transmission bandwidth of the internet exceed the express delivery capacity?

This reflects the popular expectations for internet speed which also matters to Prof. William Shieh: "Whenever the internet needs to be accelerated, it is the time when we optical communication workers exert our capabilities."

5G, big data, artificial intelligence, internet of things, metaverse, one after another, new terms have emerged in recent years, placing higher requirements on data transmission capabilities. Living in the digital world, we may have become accustomed to interactive videos, streaming media, and facial recognition payment systems, but many of us are unaware that a "capacity crunch" is quietly approaching.

How long can our current communications network transmission technology last? Is it still possible to ask for more capacity from fiber? How many years of speed and capacity can new technology in the laboratory reserve for the internet?

Preparing for the future is a career that Dr. Shieh has pursued now for 30 years. Former professor from the Department of Electrical and Electronic Engineering at the University of Melbourne, Australia, recently joined the Westlake University School of Engineering full time as a Chair Professor of Optical Communication and Sensing. How does he answer the abovementioned questions?

Prepare for the Future of the Internet

In 1989, Shieh graduated from the University of Science and Technology of China with a bachelor's degree in physics and received PhD Scholarship from the China-US Physics Examination and Application (CUSPEA). The program, chaired by Nobel Laureate Dr. Tsung-Dao Lee, selects and sends top-talented students to the United States to pursue PhD studies in physics.

Also in that very year, the world's first commercial internet service provider, in the form of dial-up internet access, began its commercial offering .

Shieh was admitted to the Department of Physics at the University of Southern California. In China at that time, ordinary people might not have even heard of the internet, so naturally Shieh also knew little about communications.

Two years after admission, a new professor arrived in the school's electrical engineering department. Ever since the invention of the telephony, Bell Labs has been operated at the forefront of innovation in communications. The new professor, Alan Willner, was from Bell Labs and intended to carry out research related to optical fiber communications.

Shieh studies physics, especially in the field of optics. Optical fiber communications at that time was still very much an emerging field. Although he only knew optics and not communications, Shieh was attracted to this new field and boldly knocked on. Willner's door.

Humans are social animals. When the internet covers the whole globe, it opens up our imagination for faster communication. In the past 20 years, thanks to the continuous development of optical fiber communication technology, the transmission rate of the internet has increased nearly one hundred times. 

The application of orthogonal frequency-division multiplexing (OFDM) and its related technologies in optical communication first proposed by Shieh’s team play a part in this success story.

OFDM is a signal processing method through which a more efficient and reliable multi-carrier transmission scheme can be achieved.

This form of technology was originally used in wireless communication, also known as Wi-Fi. In 2006, Shieh’s team adopted the method for coherent optical communication, and proposed that switching from single carrier to multi-carrier could greatly improve the efficiency of optical fiber communication. This theory opened up researchers' thinking as well as a new field in the optical communication community.

In the following four or five years, Shieh’s team continued to improve a series of theoretical and experimental studies related to OFDM and multi-carriers. At the same time, more laboratories and communications manufacturers began to pay attention to and invest in the exploration of optical communication technology originated from multi-carrier modulation, which greatly improved the speed and capacity of communication networks.

When we open apps on mobile phones, tablets, and computers, the effortless experience we enjoy results in part from the technical achievement that a group of optical communication scientists like Shieh achieved in the past.

Around 2010, during the era of 3G networks, the bandwidth of domestic home broadband was far less than the current gigabit rate. But optical communication experts around the world had realized that bandwidth is no longer an inexhaustible resource of optical fibers. Shieh also led his students to study the capacity limit of optical fiber communication, and calculated the upper capacity limit of a single-mode optical fiber.

If we follow the existing path and limit ourselves to the standard single-mode fiber, then it is obvious the "capacity ceiling" of internet data transmission will emerge rapidly in the future. It is also obvious that with the rapid development of artificial intelligence technology and the mobile internet, new concepts such as the metaverse have put forward requirements of completely higher orders of magnitude for data transmission capabilities.

Then what do we do?

We can use the common concept of the information superhighway to think about this challenge. In order to ensure the stability of transmission, experts used to think that the fiber must be single-mode -- that is, the data runs in a single lane. If you want to run more cars, the most direct way is to open more lanes.

Shieh believes, however, that with the development and improvement of technology, we can completely break free from the limitations of the single mode.

In 2011, Shieh’s team published a post-deadline paper (PDP) at the Optical Fiber Communication Conference (OFC), and took the lead in proposing optical space division multiplexing technology to the world for the first time. This is a few-mode transmission that overcomes the capacity limitation of single-mode fiber, and creates a new generation of large-capacity fiber communication technology, which will increase the transmission capacity drastically in the future.

At the same time, Bell Labs in the United States and Europe also published space division multiplexing technology during the same conference, and its influence should not be understated. In the optical communications industry, this technology -- one of the next-generation transmission solutions drawing the most attention -- and is considered to be 6G, 7G, and data transmission solutions for large data centers.

Prepare for the Future Scientific Endeavor

Shieh graduated from the University of Southern California with a Ph.D. in 1996, and did not teach at the University of Melbourne until 2004. In the intervening eight years, he worked in three industrial R&D institutions, including Bell Labs.

In those eight years, Shieh was very close to the applications of optical fiber communication technology and faced the pressure brought by the flood of data to communication networks.

When he eventually returned to the university laboratory, it was because he wanted to try doing original research from a different perspective. The two abovementioned groundbreaking achievements prove that this choice was worthwhile.

"I am proud of my research achievements at the University of Melbourne,” Shieh expressed, “which have exceeded my academic expectations and made me see my potential. The name 'William Shieh' has been recognized by the community because of my research.”

Being a scientist, for him, is also a way to prepare for the future.

Shieh has excelled at academics since his childhood. He won the first prize in Sichuan Province in a mathematics competition, and he also performed well in physics competitions. He was accepted without an entrance exam by the University of Science and Technology of China. Studying has never been too difficult for him either.

“Although before I went to the University of Science and Technology of China, my family did not know what I could do in the future by studying physics, and they were even more so at a loss when I went abroad,” Shieh recalls. But with his aptitude for studying at a young age, he seemed destined to become a scientist.

When he later devoted himself to optical fiber communication research, he viewed it as an excellent direction for his scientific career.

A similar logic guided him to return to China this year and join Westlake University. A new research university in China embracing excellence and refinement sounded like a great place for him to continue his work.

What really attracted Shieh to join Westlake University was the tacit understanding among the scientists and the same scientific language they used. For example, the university promotes interdisciplinary interactions, a value which has been incorporated into the very construction of the campus.

The OFDM application proposed by Shieh in 2006 originated from an accidental interdisciplinary exchange. At that time, he met at the airport a postdoctoral fellow in the electrical engineering department of the University of Melbourne who was studying wireless communication. When the two were drinking coffee together, Shieh asked: What is the hottest topic in your Wi-Fi field these days? The answer: OFDM.

At that time, Shieh did not know what OFDM was; the postdoc did not know what was going on with optical fiber communication. The two just talked about these topics and how OFDM can solve the problem of signal distortion in wireless communication. Dealing with the signal distortion in optical fiber communication was exactly the problem that would be racking Shieh’s brain.

Future innovations are also likely to emerge at the boundaries of different research directions and different disciplines. In addition, Westlake University strives for basic and original scientific research. Every scientist in the world knows this is a very difficult task, but it is a must if we want to achieve scientific and technological self-reliance.

Shieh is from Chongqing, a Chinese city built on mountains, so climbing the slopes is in his bones.

When he started focusing on few-mode fibers 10 years ago, he knew how difficult it was to go from zero to one. At that time, the mode couplers needed for experiments cannot be found in the universities around the world as very few could make them; almost all optical fiber manufacturers did not know how to make few-mode fibers.

Forging a new path on the boundary of human scientific exploration is easier said than done.

It took Shieh more than a year to manufacture the first few-mode fiber. Now his team is still researching optical space division multiplexing technology and few-mode fiber. At Westlake University, he hopes to further study how to better apply this technology to large-scale data centers -- namely, the "cloud" that has become more and more familiar to us.

Prepare for the Future of Innovation

Not too long ago, at the opening ceremony for this year’s new cohort of doctoral students at Westlake University, Shieh, on his second day of employment, stood on the stage with 15 other chair professors for the convocation.

This is a tradition of Westlake University. From the 19 students of our first cohort to the 352 students of this year’s sixth cohort, the university has always insisted that every new student should take the stage to complete the simple, but solemn ceremony.

Shieh agrees with this sense of ceremony. He once said that the feeling of achievement brought to him by working in a university is that he can change the world not only through his own research, but also through the students he trains.

These outstanding young people will become the innovative force that will transform the future.

Shieh hopes that doctoral students he recruits in Westlake will have the same strong internal drive in scientific research.

"Why do you want to get a doctorate? First of all, you have to understand this question. Is it because of a doctoral title, because of the expectations of your parents, or because you really want to do science?" Shieh said that only after thinking about this question can we talk about adventures, going against the current, and doing unique research.

Since 1991, when he studied optical fiber communication under Prof. Willner, Shieh has always maintained a strong sense of belief in this subject and the importance of optical communication. He knows that only by believing in his research will he be willing to put in endless efforts and “jump into the unknown”.

As a doctoral advisor, Prof. Shieh is not productive in the traditional sense. During his 18 years at the University of Melbourne, he trained only 17 Ph.D. students. He has this requirement for himself: No matter how busy he is, he must ensure that he has the time and energy to give students enough guidance, which is crucial early in their research career.

"The day they walk out of the laboratory, they should have their own independent academic reputation. They are no longer Shieh’s students, but inventors of new theories and new technology."

Prof. Shieh, like Westlake University, believes in the power of innovation to define the future.

Join Prof. William Shieh’s Team

Prof. Shieh received his M.S. in Electrical Engineering and Ph.D. in Physics from the University of Southern California in 1994 and 1996. He has worked in many well-known universities such as the Jet Propulsion Laboratory in Pasadena, California, and Bell Labs in Holmdel, New Jersey. Institutional work; from 2004 to 2022, he taught in the Department of Electrical and Electronic Engineering, University of Melbourne, Australia; in 2022, he returned to China to join Westlake University as a chair professor of optical communication and sensing.

Professor Shieh was elected as IEEE Fellow and OSA Fellow respectively due to his outstanding contributions to OFDM work. He was also awarded the Future Fellowship of Australia (2011-2014), and served as the chairman of the international conferences such as OFC.

After joining Westlake University, Shieh plans to carry out extensive research in the field of optical communication and sensing for a long time to come. Recruitment for scientific research talent in related fields is now open. Please click the link below for more details:

https://www.westlake.edu.cn/Careers/OpenPositions/research/