Many of the communication tools of today rely on the function of light or, more specifically, on applying information to a light wave. Up until now, studies on electronic and optical devices with materials that are the foundations of modern electronics—such as radio, TV, and computers—have generally relied on nonlinear optical effects, producing devices whose bandwidth has been limited to the gigahertz (GHz) frequency region. (Hertz stands for cycles per second of a periodic phenomenon, in this case 1billion cycles).
Thanks to research performed at the University of Pittsburgh, a physical basis for terahertz bandwidth (THz, or 1 trillion cycles per second)—the portion of the electromagnetic spectrum between infrared and microwave light—has now been demonstrated.
In a paper published March 4 in Nature Photonics, 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—dividing a single color of light into a series of evenly spaced spectral lines for a variety of uses—that spans a more than 100 terahertz bandwidth by exciting a coherent collective of atomic motions in a semiconductor silicon crystal.
"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," says Petek. "Needless to say, this has been a long-awaited discovery in the field."
To investigate the optical properties of a silicon crystal, Petek and his team investigated the change in reflectivity after excitation with an intense laser pulse. Following the excitation, the team observed that the amount of reflected light oscillates at 15.6 THz, the highest mechanical frequency of atoms within a silicon lattice. This oscillation caused additional change in the absorption and reflection of light, multiplying the fundamental oscillation frequency by up to seven times to generate the comb of frequencies extending beyond 100 THz. Petek and his team 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," says Petek. "The discovery was both the result of developing unique instrumentation and incisive analysis by the team members."
Petek notes the team's achievements are the result of developing experimental and theoretical tools to better understand how electrons and atoms interact in solids under intense optical excitation and of the invested interest by Pitt's Dietrich School in advanced instrumentation and laboratory infrastructure.
The team is currently 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. Petahertz is a unit of measure for very fast frequencies (1 quadrillion hertz).
This research was funded by a grant from the National Science Foundation.
For more information on Petek's research, visit www.ultrafast.phyast.pitt.edu/Home.html
B. Rose Huber | EurekAlert!
Product placement: Only brands placed very prominently benefit from 3D technology
07.07.2016 | Alpen-Adria-Universität Klagenfurt
NASA Goddard network maintains communications from space to ground
02.03.2016 | NASA/Goddard Space Flight Center
Ultrafast lasers have introduced new possibilities in engraving ultrafine structures, and scientists are now also investigating how to use them to etch microstructures into thin glass. There are possible applications in analytics (lab on a chip) and especially in electronics and the consumer sector, where great interest has been shown.
This new method was born of a surprising phenomenon: irradiating glass in a particular way with an ultrafast laser has the effect of making the glass up to a...
Terahertz excitation of selected crystal vibrations leads to an effective magnetic field that drives coherent spin motion
Controlling functional properties by light is one of the grand goals in modern condensed matter physics and materials science. A new study now demonstrates how...
Researchers from the Institute for Quantum Computing (IQC) at the University of Waterloo led the development of a new extensible wiring technique capable of controlling superconducting quantum bits, representing a significant step towards to the realization of a scalable quantum computer.
"The quantum socket is a wiring method that uses three-dimensional wires based on spring-loaded pins to address individual qubits," said Jeremy Béjanin, a PhD...
In a paper in Scientific Reports, a research team at Worcester Polytechnic Institute describes a novel light-activated phenomenon that could become the basis for applications as diverse as microscopic robotic grippers and more efficient solar cells.
A research team at Worcester Polytechnic Institute (WPI) has developed a revolutionary, light-activated semiconductor nanocomposite material that can be used...
By forcefully embedding two silicon atoms in a diamond matrix, Sandia researchers have demonstrated for the first time on a single chip all the components needed to create a quantum bridge to link quantum computers together.
"People have already built small quantum computers," says Sandia researcher Ryan Camacho. "Maybe the first useful one won't be a single giant quantum computer...
14.10.2016 | Event News
14.10.2016 | Event News
12.10.2016 | Event News
25.10.2016 | Earth Sciences
25.10.2016 | Power and Electrical Engineering
25.10.2016 | Process Engineering