Photon Switch Called the Fastest of its Kind

A novel ultrafast photon switch could pave the way to a new class of sensitive receivers, faster sensors and optical-processing devices.

A team from the University of California, San Diego, created the 500-GHz photon switch, which they have already used to control photons in optical fiber channels.

“Our switch is more than an order of magnitude faster than any previously published result to date,” said professor Dr. Stojan Radic. “That exceeds the speed of the fastest lightwave information channels in use today.”

The researchers used a three-photon input to manipulate a watt-scale beam at a speed exceeding 500 GHz. They found that a 2.5-ps pulse with a peak power of 178 nW contains less than three photons, proving that photon switches at this rate are feasible.

Radic said two key contributors to synthesizing the photon gate include “the ability to predict the optimal microscopic variation and our ability to measure such variations in physical fiber.”

Ultrafast control of a strong optical beam by a few photons has long been a challenge, and one that had previously limited the performance of sensors and optical-processing devices, the researchers wrote in the study.

The study demonstrated that such fast control becomes possible in fibers made of silica glass — the resulting silica fiber presents very low optical loss, in addition to “exceptional transparency and kilometer-scale interaction lengths,” the researchers said.

Using a new measurement technique, the team was able to show that “a silica fiber core can be controlled with subnanometer precision and be used for fast, few-photon control,” Radic said, adding that the team was able to measure lengths of fiber without damaging it.

“The technology could be implemented for photon sensors that operate in fields that were previously not deemed possible based on the current technology roadmap,” Radic said.

The researchers are now engineering a new class of fibers that would further enhance ultrafast control and photon switching.

The research was published in Science (doi: 10.1126/science.1253125).

For more information, visit www.ucsd.edu.