When light passes through materials, it typically changes direction and bends in predictable ways. This change in direction, known as refraction, is caused by a change in the speed of light as it enters a new medium. In some rare cases, however, light bends differently, specifically in the opposite direction, and this is known as negative refraction. This unusual change in direction can be leveraged to develop a wide range of advanced technologies, including advanced imaging systems and small optical devices.
Researchers at the University of Hong Kong recently demonstrated negative diffraction in a magnetic semiconductor leveraging excitons (i.e., bound electron-hole pairs). Their paper, published in Nature Nanotechnology, also reports the development of an integrated nanophotonic chip that acts as a hyperlens, an optical component that can resolve extremely small details.
"Our research originated from a longstanding question: can light be manipulated in unconventional ways?" Jingwen Ma, first author of the paper, told Phys.org.
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