The structure developed by his team, says Gan, has the unique ability to arrest the progress of terahertz (THz) light waves at multiple locations on the structure's surface and also at different frequencies.
"Previous researchers have reported the ability to slow down one single wavelength at one narrow bandwidth," says Gan. "We've succeeded in actually stopping THz waves at different positions for different frequencies.
"Our next goal is to develop structures that extend this capability to the near infrared and visible ranges of the spectrum, where optical communications signals are transferred."
The Lehigh researchers report in PRL that their key innovation is a "metallic grating structure with graded depths, whose dispersion curves and cutoff frequencies are different at different locations."
In appearance, this grate resembles the pipes of a pipe organ arranged side by side and decreasing gradually in length from one end of the assembly to the other.
The degree of grade in the metal grate can be "tuned," says Gan, by altering the temperature and modifying the physical features on the surface of the structure.
Likewise, he says, temperature and surface structure can also be adjusted to trigger the release of the light signals after they have been slowed or trapped.
"The separation between the adjacent localized frequencies can be tuned freely by changing the grade of the grating depths," Gan says. "And the propagation characteristics of the trapped surface modes can be controlled by the surface geometry."
By "opening a door to the control of light waves on a chip," says Bartoli, the new Lehigh gratin
|Contact: Kurt Pfitzer|