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A new optical effect in nanoscale disks of silicon, namely patterns of radiation that do not emit or scatter light, has been observed by A*STAR researchers and international collaborators. These modes, which have never before been observed at visible wavelengths, could be used in tiny lasers that are not much bigger than viruses.

A fundamental principle of electromagnetism is that an accelerating electric charge will emit light, losing energy in the process. But, the possibility of creating special configurations of electrical current that do not radiate has intrigued physicists for many decades. Such configurations may serve as possible models of stable atoms, which do not emit radiation despite having orbiting electrons.

A fascinating example of such a non-radiating source is known as an anapole—a distribution of charges and currents that does not radiate or interact with external electromagnetic fields. Elementary particles that exhibit anapole modes have been proposed as a potential source of the mysterious dark matter, which accounts for about 25 per cent of the mass and energy of the observable Universe, but is invisible to astronomers.

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