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Optical oscilloscope could be ‘game-changer’ for communications

Technology News |
By Rich Pell


The device, say the researchers, converts light oscillations into electrical signals, much like hospital monitors convert a patient’s heartbeat into electrical oscillation. Until now, reading the electric field of light has been a challenge because of the high speeds at which light waves oscillates.

Today’s most advanced techniques, such as those used in communications, can currently clock electric fields at up to gigahertz frequencies – covering the radio frequency and microwave regions of the electromagnetic spectrum. Light waves oscillate at much higher rates, allowing a higher density of information to be transmitted, however current tools for measuring light fields could resolve only an average signal associated with a ‘pulse’ of light, and not the peaks and valleys within the pulse.

Measuring those peaks and valleys within a single pulse is important, say the researchers, because it is in that space that information can be packed and delivered. Complete characterization of optical waveforms requires an ‘optical oscilloscope’ capable of resolving the electric-field oscillations with sub-femtosecond resolution and with single-shot operation.

“Fiber optic communications have taken advantage of light to make things faster, but we are still functionally limited by the speed of the oscilloscope,” says Physics Associate Professor Michael Chini, who worked on the research at UCF. “Our optical oscilloscope may be able to increase that speed by a factor of about 10,000.”

With their device, the researchers showed that strong-field nonlinear excitation of photocurrents in a silicon-based image sensor chip can provide the sub-cycle optical gate necessary to characterize carrier-envelope phase-stable optical waveforms in the mid-infrared. By mapping the temporal delay between an intense excitation and weak perturbing pulse onto a transverse spatial coordinate of the image sensor, say the researchers, they showed that the technique allows single-shot measurement of few-cycle waveforms.

The next step, say the researchers, is to see how far they can push the speed limits of the technique. For more, see “Single-shot measurement of few-cycle optical waveforms on a chip.”


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