Researchers have confined light to dimensions smaller than the diffraction limit in a nanosized dielectric cavity for the first time. The work, which confirms a theoretical prediction made in 2006, could promote the development of new optical chip architectures that consume less energy than their electrical counterparts.
Classical optics theory states that light cannot be focused into a volume smaller than a cube with a side-length of half its wavelength. This is the diffraction limit, and it restricts the resolution of optical microscopes. In recent years, however, researchers used metal nanoparticles to compress rather than focus light. This compressed light is more intense and interacts more strongly with matter.
The problem with metal nanoparticles, however, is that they absorb light as well as compressing it, leading to optical losses. Particles made from dielectric materials ought to be better, since they do not absorb light as strongly, and in 2006, a team led by Michael Lipson at Columbia University in the US showed that substituting them should, in theory, work.
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