March 9, 2012
Move Over GHz, Terahertz Bandwidth Could Make Smartphones 1,000 Times Faster
Peter Suciu for RedOrbit.com
While those Verizon and AT&T commercials may claim that the respective carrier has the “fastest” network for mobile phones, new communications technology could make today´s 3G and 4G networks look as antiquated as the telegram.
The whole gigahertz frequency could be made obsolete as a team of researchers at the University of Pittsburgh look to develop a terahertz frequency that could provide a means of transmitting data thousands of times faster. The researchers have developed a frequency comb with more than 100 terahertz of bandwidth, and this could be a major leap in the technology.
The research has so far demonstrated a physical basis for the terahertz bandwidth, which is the portion of electromagnetic spectrum that exists between infrared and microwave light. Up until now the studies on electronic and optical devices with materials that are the foundation of modern electronics — with everything from radios to TVs to computers — have essentially relied on nonlinear optical effects. The result has been that these devices have been limited to the gigahertz (GHz) frequency region. The research at the University of Pittsburgh has demonstrated the basis for terahertz bandwidth.
The team led by Hrvoje Petek, a professor of physics and chemistry in Pitt's Kenneth P. Dietrich School of Arts and Sciences, and his colleague Muneaki Hase, a professor of applied physics at the University of Tsukuba in Japan and a visiting scientist in Petek´s lab, detail their success in generating a frequency comb, which “spans a more than 100 terahertz bandwidth by exciting a coherent collective of atomic motions in a semiconductor silicon crystal.”
The research was published in the March 4 editor of Nature Photonics.
“The ability to modulate light with such a bandwidth could increase the amount of information carried by more than 1,000 times when compared to the volume carried with today's technologies,” Hyoje Petek said in a statement. “Needless to say, this has been a long-awaited discovery in the field.”
The team investigated the optical properties of a silicon crystal, and examined the change in reflectivity after excitation with an intense laser pulse. This followed an excitation, where the team observed that the amount of reflected light oscillates at 15.6 THz, which is reportedly the highest mechanical frequency of atoms within a silicon lattice. It was found that this oscillation caused additional change in the absorption and reflection of light, further multiplying the fundamental oscillation frequency by up to seven times to generate the comb of frequencies extending beyond 100 THz.
Petek and his team noted that they were able to observe the production of such a comb of frequencies from a crystalline solid for the first time.
“Although we expected to see the oscillation at 15.6 THz, we did not realize that its excitation could change the properties of silicon in such dramatic fashion. The discovery was both the result of developing unique instrumentation and incisive analysis by the team members.”
And before anyone gets too satisfied with terahertz, it should be noted that the researchers are now investigating the coherent oscillation of electrons, which could further extend the ability of harnessing light-matter interactions from the terahertz- to the petahertz-frequency range.
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