Terahertz computing may not be dead after all

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Terahertz computing may not be dead after all

Salt Lake City (UT) – The Gigahertz race was probably one of the most ill-fated ideas in the microprocessor industry in the late 1990s and early 2000s. Intel was almost brought down to its knees by the enormous power consumption and heat dissipation of 3+ GHz speeds in circuits of the time, eventually hitting a wall at 4 GHz. The Gigahertz race has now become a multi-core race, but scientists have ideas to ramp up the clock speed at a faster pace again: Terahertz computers may be within reach  – if data is carried over optical instead of electrical circuits.

Researchers at the University of Utah have not given up on the idea of dazzling clock speeds in processors, reminding us of landmark comments made by Intel’s Pat Gelsinger back in 2001: Back then, the executive said that 30 to 40 GHz may be reached by 2010, requiring nuclear power plant-like energy systems within PCs. Ajay Nahata, a University of Utah professor of electrical and computer engine, believes that clock speeds, which are stalling in the range of 3 to 4 GHz today, could grow at a faster pace again within the next years, if systems design will take advantage of optical technologies. Within ten years, Nahata said, superfast far-infrared computers could become commercially available.      

Nahata’s statement is based on initial research that investigated circuits that that run on far-infrared light instead of electricity. Apparently the scientist and his team were able to create the equivalent of wires that carried and bent this form of light (also known as terahertz radiation), which is believed to be the last unexploited portion of the electromagnetic spectrum.

A report that will be published April 18 in the online journal Optics Express, will provide further details on Nahata’s results and a test setup that stainless steel foil sheets with patterns of perforations that successfully served as wire-like waveguides to transmit, bend, split or combine terahertz radiation. The long-term goal of the research is to develop capabilities to create circuits that run faster than modern-day electronic circuits “so we can have faster computers and faster data transfer via the Internet,” according to the scientist.

The setup included pieces of stainless steel foil measuring 4” x 1” in area size and 625 microns thickness – or 6.25 times the thickness of a human hair. The scientists perforated the metal with rectangular holes, each measuring 500 microns by 50 microns. The rectangular holes were arranged side by side in three different patterns to form “wires” for terahertz radiation – one of which “successfully” carried terahertz radiation in a straight line, while two changed the direction the terahertz radiation was moving through splitting or coupling.

The project did not yet yield a 1 THz speed, but was in the range of what is defined as terahertz radiation – 0.1 THz to 10 THz. The scientists said they chose to run a frequency “they could generate and measure”: About 0.3 THz (300 GHz).

“Electronic circuits today work at gigahertz frequencies – billions of cycles per second,” Nahata stated. “In this study, we’ve demonstrated the first step toward making circuits that use terahertz radiation and ultimately might work at terahertz speeds or a thousand times faster than today’s gigahertz-speed computers.”

While research on terahertz waveguides have existed for about a decade, Nahata claims that his team was able to show “how to make these waveguides on a flat surface so that you can make circuits just like electronic circuits on silicon chips.”

“All we’ve done is made the wires” for terahertz circuits, Nahata says. “Now the issue is how do we make devices [such as switches, transistors and modulators] at terahertz frequencies””