One day in the spring of 1987, Eli Yablonovitch and Sajeev John got together for a lunch they both remember well. The two researchers had never met. They got in touch after discovering that each had submitted a paper to Physical Review Letters based on the same novel idea— an idea now considered groundbreaking.
Yablonovitch was an electrical engineer at Bell Communications Research, or Bellcore, in Red Bank, New Jersey. He was already known for his work refining a laser that would become a mainstay of fiber-optic communications. John was a promising theoretical physicist; he had recently joined the faculty at Princeton University. When they sat down together, in the civilized surroundings of a Princeton dining hall, the sociobiological dynamic was that of two large dogs sniffing each other.
"The conversation was lively," recalls John.
"The meeting was lively, but it was also a little tense," Yablonovitch says. Both men knew they were onto something big, though each concluded his paper with only modest predictions. Yablonovitch said the idea "may someday have a role to play in the study of semiconductor lasers." John's paper said only that it "may lead to a number of useful device applications." Both conclusions now look like massive understatements. These days hundreds of papers come out of dozens of labs all over the world citing those 1987 papers. Back then, however, Yablonovitch and John were alone. Being a lone genius can be gratifying. But having a rival can be reassuring: It suggests you're not a crazy lone genius.
The two men finished lunch on amicable terms. They also agreed on a name for their idea: It should be called a photonic band gap. Their idea has since been realized in the form of photonic crystals, which could prove as far-reaching an innovation as semiconductors. Photonic crystals have the regular lattice structure of natural crystals. They look a bit like cages, and that's just what they are. They're cages that trap photons— particles of light that move at 186,000 miles per second— like fireflies in a jar.
