Slowing light to speed data: USC Viterbi School wins $4.3M photonics IT contract

But Willner says the new optical system he and Hellwarth are building will provide another way, in which data can stay photonic and pass through at extremely high speed.

Their technique is to convert the photonic information from one color to another one, and then pass the data through an element that has a speed of light which is dependent on the color of the light - i.e., red photons could travel slower than blue photons. Each photonic data stream is given its own "color," or delay value, and then seamlessly woven together and sent on their common way without ever going through an electronic interface.

Willner has already succeeded in efficiently delaying a single 80-Gigabit/s data stream and multiplexing two separate 40-Gigabit/sec data streams. His plans call for upping capacity to the 100's-of-Gigabit/sec range.

Multiplexing is only part of the suite of applications. Another is buffering. A complete rundown of the benefits of a tunable system from the proposal: it could allow "accurate synchronization for bit-level interleaving, time-slot interchange, multiplexing and demultiplexing, time switching, and data packet synchronization."

The system that the USC team proposes comes out of recent research by Willner and others worldwide in creating systems that use new techniques to slow light down. For all these applications, a high degree of delay control is needed in the ability to continuously tune the timing of the high-speed-data flow.

The design goal is a system that can tunably slow light from 0 up to 5 microseconds - that is, a slowed stream can arrive up to 5 microseconds later than an untreated on; the 5 microsecond delay would require a roughly 50 fold improvement on their current published value of 100 nanoseconds.

To put this in perspective, a delay of 5 microseconds for a 500-Gbit/sec data stream is the same as delaying a data stream by millions of bits, an amount that could open up many possible applications.

Willner has published a series of papers in the last two years describing steady improvements in both the amount of slowing achieved and control over the process. Key to the proposed tunable system is extremely sophisticated laser technology.

Hellwarth, a member of both the National Academy of Sciences and the National Academy of Engineering, is internationally recognized for his photonics work, including both his invention of giant pulse lasers and his studies of the effects of lasers upon materials.