Roger Stolen explains fiber drawing at the Fiber & Electro-Optic Research Center draw tower.
When Roger Stolen joined the Virginia Tech faculty this past summer, he came with a truckload of equipment, 30 years' experience as one of AT&T Bell Labs' fiber optics pioneers - and a host of unanswered optics questions.
Stolen has been in "the fiber business" since the early days of optical communications, and has worked in every aspect of the field. He has been involved with making fibers, studying their properties, making components, and studying the physics of optical effects.
A developer of the fiber Raman and soliton lasers, and the first to demonstrate polarization-preserving fibers, Stolen has followed a career that several times has taken new direction from discoveries and serendipitous events.
While studying for his Ph.D. in solid state physics at the University of California at Berkeley in the early 1960s, Stolen entered the world of lasers. "At that time, lasers were for EEs," he said. "Physicists had not picked up on them yet, but my advisor, Klaus Dransfeld, was interested in optics."
After studying lasers as a post-doctoral fellow at the University of Toronto, he intended to return to California, but "My boss at Toronto, Boris Stoicheff, shipped me to Bell Labs in New Jersey...It was a great job, but my intent was to stay for about five years, then head back west. Thirty years later I was still at Bell Labs, and for all practical purposes, had become an engineer!"
At Bell Labs, Stolen started out working with lasers, solid state optics, and far infrared spectroscopy. "Then optical fibers appeared. I got asked a lot of questions, because I'd been interested in properties of glasses. There were some real mysteries about glasses."
He teamed up with Eric Ippen and Arthur Ashkin to experiment on some of the first Corning fibers. In 1971, they were the first to demonstrate that optical fibers have nonlinear characteristics. In 1980 Stolen, Linn Mollenauer and Jim Gorden first observed solitons in optical fibers. Solitons are ultrashort pulses that travel great distances without spreading. Soliton and soliton-like communication systems are currently being developed for long-distance underwater and terrestial fiber networks.
"Finding the nonlinear effects in fibers headed me in a totally different direction," Stolen said. "We then worked through all the different effects in optical fibers."
"As part of this, we realized we needed to make fibers ourselves," he said. "We needed fibers with special properties. I inherited an old German watchmaker, and we made the first polarization preserving fibers, then went on to invent several kind of fibers and special fiber devices. Polarization preserving fibers simplify optical circuits that involve the interconnection of planar and fiber devices."
"That went well until my watchmaker retired," he commented. "Then I went off into fiber measurements associated with the submarine cable division - now Tyco Submarine Systems."
When AT&T broke up, Stolen went with AT&T Research Laboratories as a principal member of the technical staff.
At AT&T Research, Stolen no longer needed his fiber-making equipment. He called Virginia Tech alumnus Ashish Vengsarkar at Lucent Technologies to see if he thought Tech would be interested in the equipment. "I was joking at the time that my wife was trying to get me to move south, and he told me that Tech was looking to hire EE faculty."
"Actually, I had donated the equipment to Tech before I knew I was coming here," he said. "When I did come, AT&T was kind enough to let me take some more very expensive equipment. TYCO Submarine Systems also donated a truckload of equipment to the Fiber & Electro-Optics Center (FEORC) so I am starting out with a well-equipped lab."
After 30 years in industry, how does Stolen describe his adjustment to the academic world? "I'm learning the same lesson every new faculty member does," he said. "The first time you teach a course, it soaks up your life." During his first semester he taught the undergraduate optical fiber course, and he is currently teaching graduate-level optical communications. "We're talking about developing a graduate-level course in fiber nonlinear optics, but we don't know whether or not there is a market for it," he said.
He is also busy integrating his equipment and research into the department's fiber optics program. He is investigating two general areas: special-purpose fibers and fiber components and devices. "These areas are much better scaled to university operations," he said. "There is also a lot of interest and opportunity for fibers in the visible range, such as blue and green for research purposes."
One project, funded by AT&T, involves mapping the characteristics of a device made several years ago. The device, an integrated circuit, corrects for pulse spreading in certain fibers, but decreases signal/noise. "We're trying to see where the device would be useful in actual transmission systems."
Another project involves understanding a fiber polarizer invented when Stolen was at Bell Labs. "We made 200 of the things, and only three worked well," he explained. "To bring out the basic features of the device, we made a test fiber that surprised us with all sorts of weird results. Now, in collaboration with a group in Australia, we're trying to apply what we have learned to the malfunctioning polarizers. We learned that our understanding was faulty, but how do we now get the polarizers to work?"
For Stolen, it is understanding and getting things to work that provide the fun in "the fiber business."