An expert in optics research, Chris Xu shines in the classroom as well.

Ever since his high school days, Chris Xu dreamed of becoming a college professor. So when the offer came to join the faculty in Cornell's School of Applied and Engineering Physics, where he'd earned his master's degree in 1993 and his doctorate in 1996, Xu jumped at the chance. There was only one problem: Although he was confident about the research part of the job, he'd never taught a class before and didn't know if he'd be any good at it.

"A friend at Bell Labs warned me that teaching was going to be hell,  that I would be sweating blood every day," says Xu, less than two years later. "Coming here to teach, I had this apprehension that maybe it wasn't going to work out. Then after two or three classes, I actually found it enjoyable to go to class. And after a month, I was convinced I could teach, because I could see how much the students wanted to learn. The teaching turned out very well, much better than I had anticipated."

It's a cool, rainy day at the beginning of summer, and a month after winning the Cornell Society of Engineers/Tau Beta Pi Excellence in Teaching Award, Xu is still feeling the shock. After all, there's only one award winner each year, elected by Engineering students, and for Xu to have won it his first year teaching is unheard of. But the plaque really does have his name on it, and Xu,sitting in an office that's about the size of his childhood apartment in Shanghai, speaks quickly,quietly, leaping from one metaphor to another: A new professor is like a sports car that can only drive in first gear, but the teaching itself — once he's finished the hard work of mapping out the entire semester beforehand — is like riding a locomotive, steaming forward under its own power.

He's a natural storyteller, and the words come pouring out as he talks about the excitement of finishing his fall course, "Intermediate Electromagnetism," and then his spring course,"Applied Solid State Physic s."The stories keep coming: There's the breakthrough concept for optical communications that was formulated in only three hours; the moment he first saw his future wife, as he wandered lost around Beebe Lake during his first fall break; or the last class of his fall course, when he saw his students passing notes back and forth, and worried that he ’d missed a button on his shirt. If he had, they probably hadn't noticed; actually, they were just getting ready to sing "For He's a Jolly Good Fellow" to their teacher, and Xu was the only one who couldn't see it coming.

"It didn't surprise me at all," says graduate student Anthony Johnson, who was given AEP's Trevor R. Cuykendall Memorial Award in part for his work as Xu's teaching assistant (TA). After four years at the University of Colorado and one year at Cornell, Johnson has never seen anything like the scene that closed AEP 355, but it's easy for him to understand what made Xu worth all the applause. "He's very good at relating to his students," says Johnson. "He comes across as being almost like one of them, pretty laid back. But at the same time, he assigns homework problems that are really,really challenging."

Xu's research straddles three main areas — optical fiber communications, biological imaging,and instrument design — and in a twist, he takes an out-of-the-box approach toward each of them, solving the problems of one with the tools of another. In fiber communications, building on his research at Bell Labs, Xu is modeling and experimenting in long-haul telecommunications. In biological imaging, he's returning to the field in which he worked as a graduate student, but with the input of fiber optics. The new strategy is adapting tools from optical communications to expand the possibilities of medical endoscopy. In design, the work he calls "fun and games," Xu is trying to develop "a brand new way to create a short pulse," which could then be adapted for applications in optics, imaging, and chemical sensing;l ike his best work, it borrows an idea from somewhere else, in this case, a little-used concept that "turns out to be very old, as old as my age."

At 36,waving his hands as he talks, Xu still looks young and excited, and it's hard to imagine him any other way. Born on the last day of 1967, he grew up at the height of China's Cultural Revolution, and remembers spending his early school days in the streets, shouting slogans he was too young to understand. His mother worked for the postal service, and his father, who'd grown up too poor to ever attend a day of school, worked as a machinist in a shirt factory, gradually rising to the title of chief engineer after years of inventing and reinventing the company's machinery. Taking after his father, Chris grew up fascinated by machines, and as a boy, he was constantly taking things apart, especially cuckoo clocks, which were all much harder to put back together again. At twelve years old, feeling too cramped to study in the apartment he shared with his grandmother, parents,and three sisters, Xu went away to boarding school, where one teacher encouraged him to become an engineer."He set my path," says Xu. "By now, I'm sure he wouldn't even remember the conversation, but to me it was very significant. He called me to his office and spent about ten minutes telling me that I was doing well, and that he had very high expectations of me. And he actually said, ‘I want you to go abroad.’ For six years after that, my goal was very clear: I wanted to study in the United States, to see the world out- side China."

Graduating from Fudan University in 1989 with a bachelor's degree in physics, Xu came to Cornell in 1991, when he spent a semester as Professor Joel Brock's TA in "Intermediate Electromagnetism" before joining Professor Watt Webb's biological imaging group. Webb became his mentor, modeling the kind of career Xu wanted for himself, always moving forward and constantly seeking out exciting new directions. Xu created his motto — "Do not spend more than one hour at a time in the lab," which he's typed and taped to his computer — from Webb ’s advice to "Never grab a soldering iron from a graduate student." At heart, they share a single message: Trust and challenge the people around you.

After five and half years with Webb, a telephone call from a former PhD student of Webb brought Xu to Bell Labs, where he found himself working alongside a group of Cornell Engineering alumni, including Linn Mollenauer ’58, BEP ’59, a member of the National Academy of Engineering, who's become Xu's closest collaborator. "Chris has a marvelous ability to understand what's really important, quickly grasps what the problems are,and comes up with some very creative ideas to solve them," says Mollenauer, who rejoins Xu this semester as a visiting scientist in AEP, where they plan to continue their telecommunications work together. "In every interaction, Chris tends to be the leader, the fellow who provides the ideas and much of the momentum for getting things done."

Walking through the lab he uses for his ultra-long-haul telecommunications experiments, Xu glides past a million-dollar test bed, Mollenauer's retirement gift from Bell Labs, with its 600-kilometer spools of fiber surrounding the stacks of components that Xu calls "pizza boxes." One by one, he points out the instruments sitting on a table — a high-bandwidth power splitter, a torque wrench, a fiber splicer, rattling off the cost of each. Though it looks well organized, Xu thinks it's a mess — which is good. "I always say, if a lab is too clean, it's a bad sign," he says. "It means that nobody is working."

Moving down the hallway to his other lab, Xu talks about a revolution in medicine, when photons will be able to painlessly reach beneath the skin, creating an image that can be read and diagnosed. He talks about seeing the beauty in equations, like the one scrawled on the blackboard in his office that resolves the timing jitters in long-haul transmissions, restoring light pulses to their proper places. He talks about the simple pleasures of optics, where all he needs to do is come up with an idea, grab a handful of components, assemble them into something new, and run an experiment to see if it works.

Xu has 15 patents granted or pending, and some of his best ideas have come at lunch, with 48 hours being his fastest time from initial concept to finished prototype. At Bell Labs, Xu helped create a world-record transmission capability with an idea that began at lunchtime, and he's co-authored more than 40 papers, including four book chapters, and participated in dozens of conferences. And though he feels the pain in writing grants — "It ’s like pulling teeth," he says, "writing a paper before you've done the work."— he's just been awarded two in the last two months, $520,000 from the National Institute of Health for endoscopic imaging and $550,000 from the National Science Foundation for a novel concept in ultrafast pulse generation. He is also expecting a grant from the National Cancer Institute for cancer detection and diagnostics.

"Chris is able to see right to the heart of the question," says Joel Brock, professor and director of the School of Applied and Engineering Physics. "He's not distracted by extraneous details, and whatever problem he's looking at, he's able to immediately identify the key issues and isolate them in experiments. He learns extraordinarily quickly, and from the outside, makes it look perfectly effortless. He has a real gift, not just for explaining things but for conveying his excitement about the material."

To prepare for teaching "Intermediate Electromagnetism," Xu borrowed an old set of solutions from Brock, and though the handwriting seemed familiar, it took Xu 10 pages before he realized he was looking at his own work, finished a dozen years earlier when he was Brock's TA. Then,as September arrived after weeks of preparation, Xu set his lecture notes aside, and inside the classroom, he hardly looked at them. He teaches instinctively, talking off the top of his head, and always deriving his equations in front of the class.

"I take the material as a challenge for myself," says Xu. "How do I explain these complex concepts in a way that makes intuitive sense?Sure, anybody with a background in math can solve these problems the same way that I do. But that's not enough. You have to understand this intuitively, so you can close your eyes and see it happen in front of you. Only then can you create new things on top of the existing knowledge."

Outside of work,in the little time he has left after teaching, researching, and writing, Xu relaxes with his wife, Alice Li (PhD ’98,Cornell), a biologist who works in Cornell's patent office, and their two children, taking evening walks together. At home, their eight-year-old son Raymond (whose Chinese name means "light")has already overtaken Chris in classical guitar, which they've been studying together; while their two-year-old daughter Sophia (whose Chinese name means "calm") continues to teach him about patience, which helps both at home and in the classroom.

"I always remind myself that I need to be calm, calm, calm, but I set very high standards," says Xu, his thoughts moving quickly from his children to his students. "If I expect only very little out of them, they might just say,‘The professor doesn't think much of us.’ I teach my undergraduates at the graduate level, because if I set a high level of excellence, they will have to work very hard. And if they do, they will be able to compete with the best of the best."

It's a bootstrap philosophy that's worked for Xu all of his life, and even as he describes the path of his career as a pencil passing across a blank piece of paper, he's convinced that his style works best here in theStates and that this is really where he belongs. 

"I love this place," he says, talking at once about his lab, his university, his country."Life has treated me well, and I ’ve been grateful that everything I wanted to do, I did. In China, I wanted to come to the United States, so I did. I wanted to get a good education, so I did. When I was in grad school, I dreamed of working at Bell Labs, so I did. Then after five years there, I came back to Cornell to be a college professor, which has always been my plan.Really, it sounds almost unbelievable,but it is very true."

Kenny Berkowitz ’81 is a freelance writer in Ithaca