Prof. Shen Ping, pioneer of special optical fiber technology: What opportunities does optical fiber technology bring to the industry
2022-8-22
Shen Ping, Chair Professor of the Department of Electronics and Electrical Engineering, Southern University of Science and Technology, Fellow of the International Society for Optical Engineering (SPIE) and the Optical Society of America (OSA), and Chairman of the Guangdong Branch of the IEEE Photonics Society. For the past three years, he has served as vice chair of the IEEE Photonics Society. Prof. Shen Ping's research interests include: optical fiber technology, optical sensing, laser technology, silicon photonics and biomedical photonics, optical coherence tomography, Raman spectroscopy, surface-enhanced Raman scattering, and multi-omics-based Research on the application of modal deep learning and other technologies in early/precise diagnosis of cancer, prognosis prediction and optimal treatment. He has published more than 1,000 papers, with an H index of 62. Served as the chairman of large international conferences such as CLEO-PR, OECC, ACP, PGC, OGC, ICOCN, ICAIT, etc. The course project "Enabled learning: Escape Room Design" has been widely reported by mainstream media Channel News Asia, Channel U, Channel 8, Channel 5, Zhaobao, etc. in four languages. He has also produced many outstanding students, including the founders of Raintree Optical and JPT Optoelectronics.
Q We have seen a boom in fiber technology over the past few decades, and you have done a lot of pioneering work in many areas such as specialty fibers, fiber sensors, and fiber lasers. Can you talk about the top three industries that optical fiber technology has brought about great changes in your mind?
A The top three industries in my mind are laser manufacturing, sensing and broadband communications. Based on current trends, in ten years, data transmission capacity may increase by a factor of 10, and industries will continue to invest in fiber optic technology for its reliability and data transmission speed. Secure, high-speed data transmission is one of our most important needs today, so the future of the fiber optic industry is very bright.
Q Optical fiber communication has revolutionized the field of telecommunications. What are the main challenges and trends of optical fiber communication? When will human beings reach the capacity and transmission distance limit of optical fiber communication?
A Optical fiber is the information superhighway. However, the current frequency bands for optical fiber communication are limited to C and L bands (ie 1525nm-1625nm). Since Kao first proposed optical fiber communication in 1966, optical fiber loss has been reduced from 1000dB/km to today's <0.2dB/km. In 1987, David Payne and his team invented the erbium-doped fiber amplifier, which made a major contribution to the practicality of fiber-optic communication. Another 10 years later, Philip Russell and his team fabricated the first photonic crystal fiber, enabling the design and manufacture of optical fibers to be 3-dimensional, and the continued development of complex optical fiber-based devices. The main challenge and future trend in fiber optic communications today will be the development of new optical fibers to increase transmission speeds as well as data rates. A possible solution is to remove the core of the fiber (ie coreless). But hollow-core fibers are lossy due to the confinement loss of surface modes. Anti-resonant fiber is a new type of fiber, and its potential fiber loss can be even lower than that of silica fiber. I predict that the loss of anti-resonant fiber may drop to 0.1dB/km within the next three years. Humans are far from reaching the capacity and transmission distance limit of optical fiber communication. After all, the human eye can actually see light far away. Even without the help of any instruments, the furthest single star the human eye can see is V762 in Cassiopeia, which is about 16,308 light-years (1.5x10¹⁷ kilometers) away.
Q In the past few years, many special optical fibers have been developed, but ordinary commercial optical fibers still occupy the dominant position in the industry. Can you share what kind of special optical fibers may be needed in which industries, and predict what kind of special optical fibers? Can it really compete with silica fiber?
A Silica fiber will still play an important role in backbone telecommunications networks. The industry is standards-driven, traditional single-mode fiber is now cheaper than noodles in China, and the raw material supply of silica is sustainable, so the advantage is huge. I have visited one of the world's major optical fiber manufacturers, YOFC, and witnessed the company's progress in drawing optical fibers. From the information given, I calculated that their 40m high fiber draw tower makes fiber at a speed of about 200km/h. That's almost the speed of a high-speed rail. Certain applications will indeed require specialty fibers, such as biocompatible fibers, microstructured fibers, multifunctional fibers, terahertz fibers, mid-infrared fibers, nanofibers, bandgap fibers, and imaging fibers.
Q Distributed acoustic sensors (DAS) have experienced a boom in the past decade. Can you comment on its significance and application in various fields?
The advantage of A DAS is its fast distribution measurement over long distances. Based on DAS, we can realize large-scale distributed acoustic wave detection based on phase-sensitive optical time-domain reflectometry (ϕ-OTDR). DAS can be used in application scenarios such as geological sensing, oil and gas security, intrusion detection, and railway infrastructure monitoring. In recent years, many researches and techniques have been devoted to improving the performance of ϕ-OTDR sensors, including reducing measurement noise, improving dynamic measurement capabilities, sampling multiple disturbances, and improving measurement spatial resolution. I think DAS has a bright future in security, confidentiality and integrity monitoring systems.
Q fiber lasers have revolutionized the manufacturing industry and are now the mainstream laser manufacturing method. Looking forward to the next ten years, what is the development trend of fiber lasers? Are there any lasers you think are expected to match or even surpass fiber lasers in CW power and high-performance ultrashort pulse lasers, further elevating the level of manufacturing?
A fiber laser has many special properties, such as high power, good reliability, compact size, low noise and good beam quality, so it is widely used in welding, cutting, marking, printing, micromachining, drilling , welding and thermal annealing, etc. In the next decade, on the one hand, we need higher power continuous fiber lasers. On the other hand, to remove material without generating heat (i.e. avoiding melting or cracking), we will need to use femtosecond or picosecond laser pulses for thermal ablation. Therefore, we also need to develop pulsed fiber lasers with higher average power and shorter pulse time. Meanwhile, in order to develop low-cost short-pulse fiber lasers, we must study high-power optical amplifiers and high-efficiency power combiners suitable for different wavelengths. One of the competing technologies for fiber lasers may be thin-film lasers, which exhibit the advantages of high pulse energies and high average powers.
Q fiber optic endoscopes have been extensively studied. What are the advantages and disadvantages of fiberoptic endoscopy compared to other in situ sensing technologies?
A Endoscopes have two main application areas: industrial and medical. In medical applications, fiberoptic endoscopes are flexible relative to rigid endoscopes and can access non-rectal lumens and cavities. The advantages of fiberoptic endoscopes compared to fiberless endoscopes, such as capsule endoscopes, are compact size and higher optical power, and allow distal connection of photodetectors. Note that the distal photodetector is much more powerful than the proximal detector used in capsule endoscopy. With fiber optics, high-power lasers can be used for treatments such as laser ablation. I feel that the weaknesses of fiber optic endoscopes are all secondary and depend on the application, of course, it's not suitable for some scenarios that require wireless.
Q You have always been a great educator. Among your students are not only top scientists, but also founders of public companies. Can you share how the following guides different students to find the path that works best for them?
A When I was in Singapore, I generally mentored about 6 PhD students at the same time, which is the maximum number within my energies. Although the students I mentor come from all over the world, Chinese students make up the majority. As a result, many of my students have since returned to China and contributed to the development of the industry. I had a particular student who followed me for a Ph.D. with the very specific goal of starting a high-tech company. His goal was clear, so I went with it, and now the company he founded has gone public. Later, there was another bright student, I think he is very suitable for entrepreneurship. But he wasn't very clear about his goals at first, so he worked in the lab for a few years. After that, he decided to start a business, and I am confident that his company will go public sooner or later. In addition to my own students, I have assisted many young researchers to start companies early in their careers. They all did a great job, and now I turn to them from time to time for help with my own technical problems in the lab. While there is no one-size-fits-all formula for teaching, I'm happy to share my secrets. I feel that for gifted and determined students, we should reduce constraints and oversight as much as possible and replace them with enlightening, macro-advice. And we should give more time to students who have not yet found a research or life direction. I hope it's best for teachers to stay in close contact with students and work hard to create opportunities for them when they need it, to help them move up the career ladder.
Q One time we talked about one of your students who struggled with his studies for years and lost confidence in almost everything, but you managed to get him through. Can you share a few words with students who are frustrated and self-doubt about entering research?
A Basically all my PhD students graduate in about 3-4 years, and one student broke the record by doing a part-time PhD and graduating in two and a half years. The student I mentioned to you is an undergraduate. He came to me to complete the graduation project. When I accepted him, I knew he was having trouble with a lot of undergraduate courses he was supposed to complete. His lack of self-confidence permeated from his studies into his daily life, and for two years he lost the control of self-management and was even reluctant to make video calls with his parents. At the time, he was limited to one year to complete the rest of the coursework and graduation project; otherwise, he would have nothing and not get a bachelor's degree. Faced with his situation, I tried to find a way with him.
First of all, I encouraged him to take my class (EE108 Photoelectric Intelligence), so that I could better understand his study habits and ability to answer. At the same time, I took on a secret mission, often taking pictures of him and sending them to his parents, so that his parents could understand and help encourage him. Later, I changed his graduation project to something more in line with his interests. Therefore, in the end, his graduation project is no longer an optoelectronic project, but an APP for an escape room game. Through this process, I helped him rebuild his confidence in himself and hone his time management skills. In fact, he is very good, and his graduation project is very good. One of his examiners told me that he was one of the best students in his final project presentation. After graduation, he was not interested in finding a job. But I persuaded him to drop all the excuses and go get some work experience first. I've been fortunate to have many excellent students come and study with me over the past 20 years. But by supervising this student, I found that some of the students' misery is often the result of not realizing the difference between interest and curiosity. Most of the time, the learning curve is steep, and the learning journey can be arduous until we find ourselves really interested in something. Some students may choose to give up because the easiest way is to give up. They always find plenty of excuses to justify their failures, but few are willing to say "sorry" and accept room for self-improvement. There is a very good word in Chinese - "Thanksgiving", we should be grateful for all the difficulties or bad luck we experience in life. We should be grateful for all the mentors we meet and cherish the love and kindness of our parents, and use that as motivation to work hard. I advise students to try not to become stubborn too early. Because stubbornness can make a person have problems receiving information, the person needs a stronger amplified signal to receive the information. My advice to students is to be as informed as possible and embrace change with open arms. If we don't listen to and digest useful knowledge, it's hard for us to make changes. Smart people understand the importance of using the receiver (i.e. listening), while some people have been using the transmitter (i.e. speaking). Time is priceless, and some people spend too much of their time and health at a young age to make money. When they get old, they have to return the money in exchange for health, not time. While we are still young, try to learn from senior professors with a humble heart. Someday we become senior scientists, if we can build mutual trust, we should help young researchers as much as possible. When we get older, these young researchers may have accomplished more than we did, and we will be proud of our contributions to society. Those young kids will remember your birthday and call you mentor or yyds.
Q You have contributed a lot to Light: Science & Applications. How do you think this journal can promote more research and industry related to optical fiber in the future?
A I think Light can strengthen its influence in the field of fiber optic technology by organizing special issues and reviews in the field of fiber lasers, fiber optic sensors, or emerging disruptive fiber optic technologies. At the same time, I suggest that thematic forums can be organized by relying on some local conferences or international conferences. To the best of my ability, I can help organize events at this year's CIOE and ACP conferences. Special issue is also a very effective way of publicity, I have a personal experience. This year is the fifth year since the founding of the United Nations International Day of Light. One of its founders, Professor John Dudley, always carried a special issue of "Optical Fiber-Based Devices and Applications", which was written by me, Jonathan Co-edited by Knight, Jesper Laegsgaard and Dora Hu, so when Professor John Dudley told me he enjoyed reading the articles because many of them were relevant to his interests. You also know that we are about to establish a Light regional office in Shenzhen. This new office will help Light reach optical fiber companies and researchers in Shenzhen. In the next 10 years, we will work together with Light to forge ahead and reach new heights.
Q We have seen a boom in fiber technology over the past few decades, and you have done a lot of pioneering work in many areas such as specialty fibers, fiber sensors, and fiber lasers. Can you talk about the top three industries that optical fiber technology has brought about great changes in your mind?
A The top three industries in my mind are laser manufacturing, sensing and broadband communications. Based on current trends, in ten years, data transmission capacity may increase by a factor of 10, and industries will continue to invest in fiber optic technology for its reliability and data transmission speed. Secure, high-speed data transmission is one of our most important needs today, so the future of the fiber optic industry is very bright.
Q Optical fiber communication has revolutionized the field of telecommunications. What are the main challenges and trends of optical fiber communication? When will human beings reach the capacity and transmission distance limit of optical fiber communication?
A Optical fiber is the information superhighway. However, the current frequency bands for optical fiber communication are limited to C and L bands (ie 1525nm-1625nm). Since Kao first proposed optical fiber communication in 1966, optical fiber loss has been reduced from 1000dB/km to today's <0.2dB/km. In 1987, David Payne and his team invented the erbium-doped fiber amplifier, which made a major contribution to the practicality of fiber-optic communication. Another 10 years later, Philip Russell and his team fabricated the first photonic crystal fiber, enabling the design and manufacture of optical fibers to be 3-dimensional, and the continued development of complex optical fiber-based devices. The main challenge and future trend in fiber optic communications today will be the development of new optical fibers to increase transmission speeds as well as data rates. A possible solution is to remove the core of the fiber (ie coreless). But hollow-core fibers are lossy due to the confinement loss of surface modes. Anti-resonant fiber is a new type of fiber, and its potential fiber loss can be even lower than that of silica fiber. I predict that the loss of anti-resonant fiber may drop to 0.1dB/km within the next three years. Humans are far from reaching the capacity and transmission distance limit of optical fiber communication. After all, the human eye can actually see light far away. Even without the help of any instruments, the furthest single star the human eye can see is V762 in Cassiopeia, which is about 16,308 light-years (1.5x10¹⁷ kilometers) away.
Q In the past few years, many special optical fibers have been developed, but ordinary commercial optical fibers still occupy the dominant position in the industry. Can you share what kind of special optical fibers may be needed in which industries, and predict what kind of special optical fibers? Can it really compete with silica fiber?
A Silica fiber will still play an important role in backbone telecommunications networks. The industry is standards-driven, traditional single-mode fiber is now cheaper than noodles in China, and the raw material supply of silica is sustainable, so the advantage is huge. I have visited one of the world's major optical fiber manufacturers, YOFC, and witnessed the company's progress in drawing optical fibers. From the information given, I calculated that their 40m high fiber draw tower makes fiber at a speed of about 200km/h. That's almost the speed of a high-speed rail. Certain applications will indeed require specialty fibers, such as biocompatible fibers, microstructured fibers, multifunctional fibers, terahertz fibers, mid-infrared fibers, nanofibers, bandgap fibers, and imaging fibers.
Q Distributed acoustic sensors (DAS) have experienced a boom in the past decade. Can you comment on its significance and application in various fields?
The advantage of A DAS is its fast distribution measurement over long distances. Based on DAS, we can realize large-scale distributed acoustic wave detection based on phase-sensitive optical time-domain reflectometry (ϕ-OTDR). DAS can be used in application scenarios such as geological sensing, oil and gas security, intrusion detection, and railway infrastructure monitoring. In recent years, many researches and techniques have been devoted to improving the performance of ϕ-OTDR sensors, including reducing measurement noise, improving dynamic measurement capabilities, sampling multiple disturbances, and improving measurement spatial resolution. I think DAS has a bright future in security, confidentiality and integrity monitoring systems.
Q fiber lasers have revolutionized the manufacturing industry and are now the mainstream laser manufacturing method. Looking forward to the next ten years, what is the development trend of fiber lasers? Are there any lasers you think are expected to match or even surpass fiber lasers in CW power and high-performance ultrashort pulse lasers, further elevating the level of manufacturing?
A fiber laser has many special properties, such as high power, good reliability, compact size, low noise and good beam quality, so it is widely used in welding, cutting, marking, printing, micromachining, drilling , welding and thermal annealing, etc. In the next decade, on the one hand, we need higher power continuous fiber lasers. On the other hand, to remove material without generating heat (i.e. avoiding melting or cracking), we will need to use femtosecond or picosecond laser pulses for thermal ablation. Therefore, we also need to develop pulsed fiber lasers with higher average power and shorter pulse time. Meanwhile, in order to develop low-cost short-pulse fiber lasers, we must study high-power optical amplifiers and high-efficiency power combiners suitable for different wavelengths. One of the competing technologies for fiber lasers may be thin-film lasers, which exhibit the advantages of high pulse energies and high average powers.
Q fiber optic endoscopes have been extensively studied. What are the advantages and disadvantages of fiberoptic endoscopy compared to other in situ sensing technologies?
A Endoscopes have two main application areas: industrial and medical. In medical applications, fiberoptic endoscopes are flexible relative to rigid endoscopes and can access non-rectal lumens and cavities. The advantages of fiberoptic endoscopes compared to fiberless endoscopes, such as capsule endoscopes, are compact size and higher optical power, and allow distal connection of photodetectors. Note that the distal photodetector is much more powerful than the proximal detector used in capsule endoscopy. With fiber optics, high-power lasers can be used for treatments such as laser ablation. I feel that the weaknesses of fiber optic endoscopes are all secondary and depend on the application, of course, it's not suitable for some scenarios that require wireless.
Q You have always been a great educator. Among your students are not only top scientists, but also founders of public companies. Can you share how the following guides different students to find the path that works best for them?
A When I was in Singapore, I generally mentored about 6 PhD students at the same time, which is the maximum number within my energies. Although the students I mentor come from all over the world, Chinese students make up the majority. As a result, many of my students have since returned to China and contributed to the development of the industry. I had a particular student who followed me for a Ph.D. with the very specific goal of starting a high-tech company. His goal was clear, so I went with it, and now the company he founded has gone public. Later, there was another bright student, I think he is very suitable for entrepreneurship. But he wasn't very clear about his goals at first, so he worked in the lab for a few years. After that, he decided to start a business, and I am confident that his company will go public sooner or later. In addition to my own students, I have assisted many young researchers to start companies early in their careers. They all did a great job, and now I turn to them from time to time for help with my own technical problems in the lab. While there is no one-size-fits-all formula for teaching, I'm happy to share my secrets. I feel that for gifted and determined students, we should reduce constraints and oversight as much as possible and replace them with enlightening, macro-advice. And we should give more time to students who have not yet found a research or life direction. I hope it's best for teachers to stay in close contact with students and work hard to create opportunities for them when they need it, to help them move up the career ladder.
Q One time we talked about one of your students who struggled with his studies for years and lost confidence in almost everything, but you managed to get him through. Can you share a few words with students who are frustrated and self-doubt about entering research?
A Basically all my PhD students graduate in about 3-4 years, and one student broke the record by doing a part-time PhD and graduating in two and a half years. The student I mentioned to you is an undergraduate. He came to me to complete the graduation project. When I accepted him, I knew he was having trouble with a lot of undergraduate courses he was supposed to complete. His lack of self-confidence permeated from his studies into his daily life, and for two years he lost the control of self-management and was even reluctant to make video calls with his parents. At the time, he was limited to one year to complete the rest of the coursework and graduation project; otherwise, he would have nothing and not get a bachelor's degree. Faced with his situation, I tried to find a way with him.
First of all, I encouraged him to take my class (EE108 Photoelectric Intelligence), so that I could better understand his study habits and ability to answer. At the same time, I took on a secret mission, often taking pictures of him and sending them to his parents, so that his parents could understand and help encourage him. Later, I changed his graduation project to something more in line with his interests. Therefore, in the end, his graduation project is no longer an optoelectronic project, but an APP for an escape room game. Through this process, I helped him rebuild his confidence in himself and hone his time management skills. In fact, he is very good, and his graduation project is very good. One of his examiners told me that he was one of the best students in his final project presentation. After graduation, he was not interested in finding a job. But I persuaded him to drop all the excuses and go get some work experience first. I've been fortunate to have many excellent students come and study with me over the past 20 years. But by supervising this student, I found that some of the students' misery is often the result of not realizing the difference between interest and curiosity. Most of the time, the learning curve is steep, and the learning journey can be arduous until we find ourselves really interested in something. Some students may choose to give up because the easiest way is to give up. They always find plenty of excuses to justify their failures, but few are willing to say "sorry" and accept room for self-improvement. There is a very good word in Chinese - "Thanksgiving", we should be grateful for all the difficulties or bad luck we experience in life. We should be grateful for all the mentors we meet and cherish the love and kindness of our parents, and use that as motivation to work hard. I advise students to try not to become stubborn too early. Because stubbornness can make a person have problems receiving information, the person needs a stronger amplified signal to receive the information. My advice to students is to be as informed as possible and embrace change with open arms. If we don't listen to and digest useful knowledge, it's hard for us to make changes. Smart people understand the importance of using the receiver (i.e. listening), while some people have been using the transmitter (i.e. speaking). Time is priceless, and some people spend too much of their time and health at a young age to make money. When they get old, they have to return the money in exchange for health, not time. While we are still young, try to learn from senior professors with a humble heart. Someday we become senior scientists, if we can build mutual trust, we should help young researchers as much as possible. When we get older, these young researchers may have accomplished more than we did, and we will be proud of our contributions to society. Those young kids will remember your birthday and call you mentor or yyds.
Q You have contributed a lot to Light: Science & Applications. How do you think this journal can promote more research and industry related to optical fiber in the future?
A I think Light can strengthen its influence in the field of fiber optic technology by organizing special issues and reviews in the field of fiber lasers, fiber optic sensors, or emerging disruptive fiber optic technologies. At the same time, I suggest that thematic forums can be organized by relying on some local conferences or international conferences. To the best of my ability, I can help organize events at this year's CIOE and ACP conferences. Special issue is also a very effective way of publicity, I have a personal experience. This year is the fifth year since the founding of the United Nations International Day of Light. One of its founders, Professor John Dudley, always carried a special issue of "Optical Fiber-Based Devices and Applications", which was written by me, Jonathan Co-edited by Knight, Jesper Laegsgaard and Dora Hu, so when Professor John Dudley told me he enjoyed reading the articles because many of them were relevant to his interests. You also know that we are about to establish a Light regional office in Shenzhen. This new office will help Light reach optical fiber companies and researchers in Shenzhen. In the next 10 years, we will work together with Light to forge ahead and reach new heights.
