Future Optics: Inspiring interactions build a future in optical communications

OSA: What got you into optics?

Alan Willner: I was studying for a master's in electronic engineering at Columbia and one of my professors, Richard Osgood, invited me to do a doctorate with him. One of several job offers I had when I graduated was for a postdoc at Bell Labs. I had no idea what they meant by optical communications with "wavelength-division multiplexing" when I went to interview with Ivan Kaminow. It was in a small building, but the people there were giants. I needed seasoning, and here were these wonderful people whom I could learn from, so I took the job even though it was the lowest-paying, least-secure offer. I really owe Ivan so much.

That was 1988, the year when the first transatlantic undersea fiber cable was turned on at 280 Mbits/s, and we were doing gigabits in the lab. Getting into a field about to take off was unbelievably fortunate, and so was getting to know luminaries like Ivan and Tingye Li.

OSA: How did you get so active in The Optical Society?

AW: It started with Tingye. He exposed me to the people, the staff, and the volunteers who are all the heart and soul of the society. I learned that there was an entire world beyond just where you work, and a whole new level of satisfaction by serving that larger community.

It really started when Rich Wagner asked me to become vice chair of OSA's optical communications technical group. I jumped at the chance—only later did he say that Tingye had suggested my name to him. When I went to a committee meeting, it was as if my eyes were opened. The other volunteers were incredibly friendly and helpful. They had no agenda other than being there to serve the community. The more I became involved, the more I wanted to serve and help.

OSA: How broad is the optics community?

AW: It is global. You can see it in my students. Whereas Professor Osgood and I were born in the United States—as were his advisor Ali Javan and grand-advisor Charles Townes—my students come from all over. One of my first doctoral students, William Shieh, came from China, and now teaches at the University of Melbourne in Australia. One of his first PhD students, Wei Chen, taught at the Technical University of Eindhoven in the Netherlands, and just moved to Fudan University in China as a full professor. One of her first doctoral graduates was Cheefai Tan, who came from Malaysia and returned to teach at the Technical University of Malaysia in Melaka.

I have made friends from around the world by working on conference committees, governance committees, and journal editorial boards. We become friends as we work as colleagues to serve the community. And the excellence of OSA is not limited to the technical publications and researchers. It is also that OSA has developed outstanding "best practices" for our technical and governance committees. We are a global melting pot of good ideas and excellent practices. Our volunteers then take our policies back to their home institutions around the globe.

OSA: What's coming in optical communications?

AW: Before I started at Bell Labs in 1988, a couple of distinguished people asked why I was going into fiber optics since it was a "mature" field. They thought no one would ever need the gigabits that were being talked about. But the technology took off with the erbium-doped fiber amplifier and wavelength-division multiplexing, and the Internet growth was a key driver. By 2000, each wavelength could carry 10 Gbits, and each fiber could carry dozens of wavelengths. Now it's amazing that we can send Terabits across the oceans, and people still want more bandwidth. Who would have imagined that the just-laid America-Europe Connect cable will offer total capacity of 52 Terabits across the Atlantic when fully operational?

It's no stretch to say that optical communications enabled the Internet of today. Like Moore's law of computing power, the rapid growth of fiber capacity has become part of our economy. Tingye said "don't bet against bandwidth growth," and we will have to meet that demand by technological breakthroughs.

One of today's hot trends is spatial division multiplexing, whether using fibers with multiple cores or cores that can handle the multiplexing of multiple modes. So far, experiments have multiplied fiber capacity many-fold, but we have just scratched the surface trying to further expand bandwidth. More orthogonal spatial states may offer more room. The future will bring repeated cycles of capacity growth and demand growth. There will be periodic quests for new generations of innovation to overcome physical limits once thought to be insurmountable.

For the past few decades, fiber capacity has increased about a hundred-fold every decade. We're now talking about petabits per second on a single fiber. If—and that's a big "if"—advances continue at the same pace for 100 years, we will see words like Exa-, Zetta-, Zotta-, and even Brontobits/sec (1027 bits/sec). It is thrilling to imagine the enabling technologies and potential applications for such capacity.

Moreover, single-photon systems offer different communication possibilities. At present, data rates and distances are small, and cost and complexity are large. Yet future advances in quantum repeaters and single-photon sources and detectors promise exciting possibilities in secure low-power communications over long distances.

Finally, radio has been king of the free-space communications world, with optics barely registering an impact. However, with the constant increase in needed capacity, optical links may become commonplace. Indeed, with the future ubiquity of solid-state lighting, almost any bulb potentially can be used for communications.

OSA: Where can the new American Institute for Manufacturing Integrated Photonics [AIM Photonics] take us?

AW: The idea of integrated photonics has been around for more than 40 years. To bring that idea to fruition, AIM Photonics will develop ways to cost-effectively produce high-performance photonic integrated circuits that we can use anywhere that optics brings value.

One exciting prospect is low-loss, high-bandwidth optical links within and between computer chips. Such optical interconnects are needed to enable highly efficient computer architectures, as well as increase speed and reduce power consumption. Integrated photonics could provide the high connectivity and low latency that are crucial for future high-performance computing.

Looking to the future, an advance in highly nonlinear optics could shift more signal processing into the optical realm. Integrated deeply with electronics, these optics could potentially increase speed, reduce energy use, and perform operations that neither technology could do alone.

Ultimately, it is not science fiction to think that optics will be woven into everything, but we won't even notice it because optics will be an essential enabler and behind the scenes to the user. Just think of all the optics that go into your smartphone and searches—cameras, screens, lithography, laser machining, fiber communications, and optical interconnects. To paraphrase a line from a recent James Bond movie, "We are everywhere".

Alan Willner is president of The Optical Society, steering committee chairman of the National Photonics Initiative, and Steven and Kathryn Sample Chair in Engineering at the Ming Hsieh Dept. of Electrical Engineering at the University of Southern California.

The Optical Society celebrates a century of innovation

Throughout a century of breakthroughs, The Optical Society has brought together the best minds in optics and photonics to light the future. This series reflects on that history and looks to what innovations lie ahead. For more information, please visit http://osa.org/100.