Researchers have made a significant breakthrough in thermal radiation by discovering a new method for producing spinning thermal radiation in a controlled and efficient manner using artificially structured surfaces known as metasurfaces.
Thermal radiation, caused by random fluctuations in materials, has traditionally been regarded as an incoherent signal. The emitted heat from most conventional thermal emitters has little to no circular polarization. Surprisingly, many astronomical objects’ thermal radiation reaching Earth has significant circular polarization. This intriguing phenomenon leads to the discovery of strong magnetic fields in some condensed stars, explains early universe mysteries, and even provides a possible signature of life.
Spinning thermal radiation is rare, occurring only in a few condensed stars. The research demonstrates a novel method for producing this type of radiation, which has the potential to be used in a variety of applications, such as thermal imaging and communication.
For the first time, the researchers could generate predominantly left-handed circularly polarized thermal radiation in all directions using a metasurface of an array of F-shaped structures, resulting in non-vanishing optical helicity. The team’s design achieved 39% of the fundamental limit in optical helicity. They also demonstrated that the characteristics of emitted thermal photons could be tailored by the metasurface’s symmetries, demonstrating effective control over thermal radiation in its various properties.
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