Have you ever wondered why sometimes you can clearly hear someone whispering from the other side of the room, while other times you can’t hear them at all? This mystery is typically due to the actual shape of the room you’re in and the way that the shape helps conduct sound. This mystery in part led to a recent discovery by a team of researchers at Washington University in St. Louis.
The team recently published a paper that detailed their research on helping optical devices work more efficiently and transmit data faster – all thanks to the principle that sound travels faster in a domed or curved space.
The team created an optical diode by creating two doughnut shaped optical resonators and putting everything on a circuit board. The result is that light is stopped from traveling in one direction, while traveling much faster in the other direction. This in turn allows for faster data transfer rates.
Bo Peng, a graduate student in Yang’s group and the lead author of the paper states, “This diode is capable of completely eliminating light transmission in one direction and greatly enhancing light transmission in the other nonreciprocal light transmission.”
Peng adds, “Our resonators are small enough to use in computers and future optical information processors. At present, we built our optical diodes from silica, which has very little material loss at the telecommunication wavelength. The concept can be extended to resonators made from other materials to enable easy CMOS compatibility.
“We believe that our discovery will benefit many other fields involving electronics, acoustics, plasmonics and meta-materials,” says Lan Yang, PhD, an associate professor of electrical and systems engineering at Washington University in St. Louis. “Coupling of so-called loss and gain devices using PT (parity-time)-symmetry could enable such advances as cloaking devices, stronger lasers that need less input power, and perhaps detectors that could ‘see’ a single atom.”
There are numerous industries that could benefit from these discoveries and it remains to be seen just how large an impact the findings will have. One thing is certain, this study completely changes the way we view both sound and light and the roles they play in bringing us our information more quickly.
The paper goes on to state, “More broadly, our paper shows how a concept with its roots in mathematical physics can be utilized to provide solutions to practical problems, opening new possibilities for controlling and manipulating light on-chip. PT-symmetry breaking alone is not sufficient to have nonreciprocal response; operation in the nonlinear regime is also necessary. In the linear regime, light transmission is always reciprocal regardless of whether PT-symmetry is broken or not.”
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