Courtesy of Westlake University
Someone once asked such a nonsensical question: When will the transmission bandwidth of the Internet exceed the “bandwidth” of express logistics?
The absurd way of asking questions does not hide people’s expectations of internet speed.
This kind of expectation also existed in Xie Wei’s heart. “Whenever the Internet needs to speed up, it is time for us optical communication workers to exert our capabilities.”
5G, big data, artificial intelligence, Internet of Things, meta-universe… One new term after another has come out, all of which are putting forward higher requirements for data transmission capabilities. Living in the digital world, we may have long been accustomed to short videos, streaming media, and face payments, but we don’t know that the “capacity crisis” is creeping up.
How long can the current communication network transmission technology support? Is it possible to ask for more transmission capacity from the optical fiber? How many years of speed and capacity can the new technology of the laboratory reserve for the Internet?
Storing the future is Xie Wei’s business that has not stopped in the past 30 years. The professor from the Department of Electrical and Electronic Engineering at the University of Melbourne in Australia recently joined westlake University’s School of Engineering full-time as a Chair Professor of Optical Communications and Sensing.
Do optical communication reserves the future of the Internet
In 1989, Xie Wei graduated from the University of Science and Technology of China with a bachelor’s degree in physics and received funding from the Sino-US Joint Training Physics Graduate Program (CUSPEA). The program, chaired by Nobel laureate Dr. Lee Jeong-do, selects and sends students to the United States to pursue graduate studies in physics.
It was also that year that the world’s first commercial Internet service provider began to provide commercial Internet access services in the form of dial-up Internet access.
Xie Wei was admitted to the Department of Physics at the University of Southern California. At that time in China, ordinary people may not have even heard of the Internet, and Xie Wei naturally knew very little about communication.
Two years after enrolling, a new professor came to the school’s Electrical Engineering Department. In the 1980s and 1990s, Bell Labs was at the forefront of innovation in communications. The new Professor Willner is also from Bell Labs and intends to conduct research related to optical fiber communications in the academic community.
Xie Wei studied physics, especially in optics. Optical fiber communication, in that era is still a very emerging direction, although he only understands optics and does not understand communication, but Xie Wei feels that this is a good idea.
With an inexplicable intuition, the Chinese student bravely knocked on Professor Willner’s door, and since then he has knocked on his own door in the field of optical communication research.
People are social animals, and when the Internet covers the entire earth with the possibility of communication at once, it opens up people’s unlimited imagination of this communication. Especially in the past 10 years, thanks to the continuous development of optical fiber communication technology, the transmission rate of the Internet has increased by nearly 250 times.
Among them, the application of OFDM and related technologies in coherent optical communication first proposed by Xie Wei’s team is one of the technologies that play a key role.
OFDM, translated as orthogonal frequency division multiplexing, is a way of signal processing through which a more efficient and stable multi-carrier transmission scheme can be achieved.
This is a technology originally applied to wireless communications, which is what we often call Wi-Fi. In 2006, Xie Wei’s team “transferred flowers and trees” to coherent optical communication, proposing to switch from single carrier to multi-carrier, which can greatly improve the efficiency of optical fiber communication. This theory has opened up the minds of researchers and opened up a new field.
In the following four or five years, Xie Wei’s team has continuously improved the series of theoretical and experimental research on OFDM and multicarrier. At the same time, more laboratories and communication manufacturers have begun to pay attention to and invest in the exploration of optical communication technology based on multi-carrier modulation, which has greatly improved the speed and capacity of communication networks.
If we take 2006 as the coordinates, the 4G and 5G that we are using in 10 years later are mainly used in this mode of modulation. When we open the APP on mobile phones, tablets, and computers, the smooth experience we get comes from a group of optical communication scientists like Xie Wei who have saved up the “reserve food” of technology in the past.
After OFDM, Xie Wei began to reserve a longer future.
Around 2010, in the era of 3G networks, the bandwidth of domestic home broadband was far less than the current gigabit, but optical communication experts around the world have realized that bandwidth is no longer an inexhaustible resource of optical fiber. Xie Wei also took the students to study the Shannon limit of optical fiber communication and calculated the upper capacity limit of single-mode optical fiber.
That is to say, if the idea is limited to single-mode optical fiber, then where the “capacity ceiling” of future Internet data transmission is, it is obvious. It is also obvious that with the rapid development of artificial intelligence technology and mobile Internet, new concepts such as metaversity have put forward completely different orders of magnitude requirements for data transmission capabilities.
What to do?
We can understand it with the common information highway concept. In order to ensure the stability of transmission, it was thought that optical fibers must be single-mode, that is, data runs in a single lane. If you want to pass more cars, the most direct way is to open up more lanes.
Xie Wei believes that with the development and improvement of technology, the limitations of single mode can be completely broken.
In 2011, Xie Wei’s team published a PDP article (post-deadline paper) at the Optic Fiber Communication Conference (OFC), that is, the American Optical Fiber Communication Exhibition and Seminar, taking the lead in proposing optical-space separation multiplexing technology, showing the world the first to overcome the capacity limitation of single-mode optical fiber, and once again creating a new generation of large-capacity optical fiber communication technology after OFDM. Transmission capacity will be increased in linear multiples in the future.
At the same time, the air separation multiplexing technology was also presented at this academic conference, as well as Bell Labs in the United States and Europe, and its influence should not be underestimated. In the optical communications industry, this technology is one of the next-generation transmission solutions with the highest focus at present, and is considered a data transmission solution for 6G, 7G, and large data centers.
When scientists reserve the future of human cognition
Wei Graduated from the University of Southern California in 1996 and taught at the University of Melbourne in Australia until 2004. In the intervening 8 years, he worked in three industrial R&D facilities, including Bell Labs.
In those 8 years, Xie Wei was very close to the application of optical fiber communication, facing the pressure brought by the data torrent to the communication network.
Back in the university lab, I distanced myself from the application because he wanted to try to do original research from different perspectives and mentalities. The two groundbreaking results mentioned above have proven that this choice is worthwhile.
“I am proud of my scientific research at the University of Melbourne, which exceeded my academic expectations and allowed me to see my potential, and the name ‘Xie Wei’ is also known by people in the industry because of these studies.” Xie Wei commented on his work in the academic circles.
Being a scientist is also a reserve for the future for him.
Xie Wei has been a scholar since he was a child, won the first prize in Sichuan Province in the mathematics competition, and the results of the physics competition were also good, and he was admitted to the University of Science and Technology of China in advance. Reading has never had much difficulty for him.
Although before going to the University of Science and Technology of China, my family did not know what they could do in the future when they studied physics, they were even more dazed when they went abroad. But in the eyes of a young man, since he can read, it seems natural to keep reading and becoming a scientist.
As with the idea later when he devoted himself to fiber optic communications, he thought: Being a scientist is a good idea.
It is also based on the same logic of thinking that he chose to return to China this year and join Westlake University – in China, there is a young university that takes small but refined and research-oriented as his positioning, which sounds like a good idea.
What really attracted Xie Wei to join Westlake University was the tacit understanding between scientists and the same scientific language they used.
For example, interdisciplinary intersection is advocated here, and even directly opens up and brings different disciplines closer to the physical space of campus construction.
The ofDM application proposed by Xie Wei in 2006 originated from a fortuitous interdisciplinary exchange. That day, he met a Ph.D. at the airport, also from the Department of Electrical Engineering at the University of Melbourne, who was studying wireless communications. When the two of them had coffee together, Xie Wei asked: What is the hottest topic in your Wi-Fi field recently? A: OFDM.
At that time, Xie Wei did not know what OFDM was; The Bo Hou did not know what was going on with optical fiber communication. The two just went on a topic and talked about how OFDM can solve the problem of signal distortion in wireless communication. How to deal with signal distortion in optical fiber communication was exactly the problem that Xie Wei was racking his brains to think about at that time.
Future innovations are also likely to occur in different research directions and boundaries of different disciplines.
In addition, Westlake University strives for basic and original scientific research. Every scientist in the world knows that this is a very difficult task, but if you want to achieve scientific and technological self-reliance, this is a must-do.
Xie Wei is a native of Chongqing, and climbing over the hill is carved in his bones.
When he started working on low-mode fiber 10 years ago, he knew how difficult it was to go from zero to one. At that time, the mode coupler required for experiments found many universities around the world, and no one would do it; Almost all fiber manufacturers do not know how to make less-mode fiber…
It is not easy to carve out a new path on the boundaries of human cognition.
Xie Wei spent more than a year with partners to manufacture the first low-mode optical fiber. Until now, the research on optical-null separation multiplexing technology and low-mode optical fibers has continued in his research group. At Westlake University, he hopes to further study how to better apply this technology to large data centers, the “cloud” that we are now becoming more familiar with.
The future of innovation with doctoral students
At the recent opening ceremony of the 2022 doctoral students of Westlake University, Xie Wei, who had just been in the company for only 2 days, stood on the stage with 15 other chair professors and presented the entrance gift to the “Westlake Phase VI” doctoral students.
This is a tradition at Westlake University. From the 19 new students of the “West Lake Phase I” to the 352 new students of the “West Lake Phase VI” this year, the school has always insisted that every new student must go to the stage and complete such a simple but solemn ceremony.
Xie Wei agreed with such a sense of ceremony. He once said that the sense of accomplishment brought to him by entering the university work was not only to be able to change the world through his own scientific research, but also to change the world through the students he cultivated.
These outstanding young people will become the innovative force that will change the future.
As of 2020, China has laid a total of 51.69 million kilometers of optical fiber cables, with a total length of 1292 circles around the earth. In terms of optical communication system equipment and solutions, Chinese enterprises have begun to show competitiveness in the world that cannot be ignored. The rapid development of China’s Internet, communication systems and data centers has also provided a great driving force for basic scientific research in this field.
Xie Wei hopes that the doctoral students he recruited in West Lake can have the same strong internal driving force in scientific research.
“Why study for a Ph.D., we must first think about this question. Is it because of a doctorate title, because of the expectations of parents, or because I really want to do a science. Xie Wei said that only by thinking clearly about this problem can we talk about risk-taking, talk about how to swim against the current, and do unique research.
Since 1991, when he studied optical fiber communication with Professor Willner, Xie Wei has always maintained a strong sense of faith in this discipline and the cause of optical communication. He believes that only by believing in the research he is engaged in will he be willing to make endless efforts and will “jump into the unknown” regardless of himself.
He compares it with two jumps. In English, there is a saying called jump on the bandwagon, which means “with the flow”, where the bustle goes; In scientific research, Xie Wei believes that this is naturally undesirable, but should be jumped into the unknown.
As a doctoral supervisor, Xie Wei is not “prolific”. During his 18 years at the University of Melbourne, he trained only 17 PhD students. He demanded of himself that no matter how busy he was, he would ensure that he had the time and energy to give his students enough guidance, which was crucial early in their scientific careers.
“When they walk out of the lab, they should have their own, independent academic labels, they are no longer Xie Wei’s students, but the inventors of a new theory, a new technology.”
Xie Wei is a person who has come over, and he understands that the process must be arduous, but this is the only way to make innovation reserves for the future.
And to reserve innovative strength for the future is Xie Wei, every scientist, and the mission that Westlake University believes in.