A team of researchers has developed a system that can direct light and other electromagnetic waves for signal processing without any unwanted signal reflections, building on a breakthrough “anti-laser.” This innovation could advance local area networks, photonics, and other applications.
Light in a laser bounces back and forth between two mirrors, passing through an amplifying material known as the “gain medium,” such as gallium arsenide each time. Because the light has a specific wavelength, it generates feedback that grows in intensity. However, in lasers, atoms radiate at the same frequency and direction, resulting in a focused beam of a single wavelength.
The anti-laser differs in that instead of an amplifying material, and it employs one that absorbs light – a “loss medium.” In its most basic form, the anti-laser divides a single laser beam into two and directs the two beams into each other, meeting at a paper-thin silicon wafer. The waves of light are precisely tuned to interlock and become trapped. They eventually dissipate into heat.
In their most recent work, the researchers expanded on this concept, creating a device based on “reflectionless scattering modes” (RSMs). They created a device that, rather than absorbing waves, redirected them to specific channels.
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