"Opto-Chips" Are High-Speed Communications Breakthrough

The materials are used to create polymeric electro-optic modulators, or "opto-chips." These microscopic devices perform functions such as translating electrical signals - television, computer, telephone and radar - into optical signals at rates up to 100 gigabits per second (a gigabit is 1 billion bits of information). Polymeric electro-optic materials can achieve information-processing speeds as great as 10 times those of current electronic devices and have significantly greater bandwidths than electro-optic crystals currently in use. In addition, the new materials require a fraction of a volt of electricity to operate, less than one-sixth what the 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," said Larry Dalton, a chemistry professor at both UW and USC who is the overall leader of the research and has full research teams at both universities.

The breakthrough resulted from research by Dalton; William Steier, a USC electrical engineering professor; Bruce Robinson, a UW chemistry professor; and USC graduate students Cheng Zhang and Hua Zhang. Their work is described in the April 7 edition of the journal Science.

During testing at Tacan Corp. in Carlsbad, Calif., two other co-authors of the Science article - lead author Yongqiang Shi (now of Lucent Technologies) and James Bechtel - used the devices to translate electronic cable television signals into optical signals using less than 1 volt of electricity. Researchers at Lockheed Martin Corp.'s research laboratory in Palo Alto, Calif., have since replicated those results in tests involving other applications.

Polymeric electro-optic modulators can be used for information processing; to steer radio waves and microwaves to and from telecommunications satellites; to detect radar signals; to switch signals in optical networks; and as optical gyroscopes to guide planes and missiles. They serve as a bridge between electronics and fiber optics, and they provide huge capacity with very low noise disturbance and very low power requirements. They are being tested for ultra-fast analog-to-digital conversion, optical switching elements in flat panel displays and voltage sensing for the electric utility industry, Dalton said. Currently the most commonly pursued applications include signal transduction for cable television, directional couplers or routing switches in optical communications networks, and modulators in phased-array radar systems.

"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," Dalton said.

"This technology has bandwidth to burn."

Tests indicate a single modulator measuring one micron (about .000039 inch) can provide more than 300 gigahertz of bandwidth - enough to handle all of a major corporation's telephone, computer, television and satellite traffic.

Other applications are so far ranging, Dalton said, that they even create the capability of full three-dimensional holographic projection with little or no image flicker. That makes possible a device such as the science-fictional holodeck, where characters in the "Star Trek: The Next Generation" television series and movies create elaborate holographic worlds in which they live their fantasies.

The research, paid for by grants from the National Science Foundation, the U.S. Air Force Office of Scientific Research and the Office of Naval Research, is aimed at developing new materials based on the principles of condensed-matter theory. Design and molecular synthesis are done at UW and materials are then sent to state-of-the-art production facilities at USC, where the modulators are fabricated and integrated with both silica fibers and VLSI silicon chips. (See http://www.washington.edu/newsroom/news/images/optochip.jpg for an image showing the integration of the polymer into a silicon chip.)

The electro-optic modulators in use today are grown as lithium niobate crystals and, rather than being integrated into silicon chips, must be hard wired. Besides having far less capacity and requiring substantially more electrical power than the new materials, they also have greater signal loss because of electronic interference and generate substantially more heat. The special properties of the new polymers, including low heat generation, are particularly important for futuristic device applications, Dalton said.

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Additional images available at http://uscnews.usc.edu/files/opto-chips/download.html