A Mighty Modulator
‘Opto-Chips’ fabricated from a new material are nothing short of a high-speed communications breakthrough.

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NEW POLYMERS developed by USC and University of Washington chemists and engineers appear to increase signal speeds and capacity so greatly that they promise to revolutionize telecommunications, data processing, sensing and display technologies.
The polymers are used to create electro-optic modulators, or “opto-chips.” These microscopic devices can translate electrical signals – for television, computer, telephone and radar – into optical signals at rates up to 100 gigabits per second. Opto-chips can achieve information-processing speeds as great as 10 times those of current electronic devices. They have sig-nificantly greater bandwidths than electro-optic crystals currently in use. And the new materials need only a fraction of a volt of electricity to operate, less than one-sixth what crystals require.
“These electro-optic modulators will permit real-time communication. You won’t have to wait for your computer to download even the largest files,” says chemist Larry Dalton, a professor at both USC and UW.
Indeed, tests indicate a single opto-chip can provide more than 300 gigahertz of bandwidth – enough to handle all of a major corporation’s telephone, computer, television and satellite traffic.
Polymeric electro-optic modulators can be used to process data, steer radio waves and microwaves to and from satellites, detect radar signals, switch signals in optical networks and guide planes or missiles.
Other applications are so far ranging, Dalton says, that they make feasible full 3-D holographic projection with little or no image flicker. A device such as the fictional holo-deck seen in the “Star Trek: The Next Generation” TV series might become a reality, allowing users to create elaborate holographic worlds in which they can live out their fantasies.
“It’s a critical decision-determining technology because ‘bandwidth, bandwidth, bandwidth’ – like ‘location, location, location’ in real estate – is critical in making decisions in communications technology,” says Dalton. “This technology has bandwidth to burn.”
The work of Dalton and his collaborators is described in the April 7 issue of Science. They include USC electrical engineer William Steier, UW chemist Bruce Robinson and USC graduate students Cheng Zhang and Hua Zhang. Lead author Yongqiang Shi received his doctorate in electrical engineering from USC in 1992 and was Steier’s graduate student.
Design and molecular synthesis were done at USC’s Loker Hydrocarbon Institute, where Dalton is scientific co-director, and at UW. Materials were then sent to state-of-the-art production facilities at USC’s Keck Photonic Laboratory, where the modulators are fabricated and integrated with both silica fibers and VLSI silicon chips.

– Bob Calverley

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