Zubin Jacob, Elmore Professor of Electrical and Computer Engineering

Team led by Prof. Zubin Jacob revolutionizes thermal radiation generation for applications in infrared technology

Researchers at Purdue University have made a groundbreaking discovery in the field of thermal radiation, uncovering a new method for generating spinning thermal radiation in a controlled and efficient manner using artificially structured surfaces, known as metasurfaces. The team, led by Zubin Jacob, Elmore Professor of Electrical and Computer Engineering, published its findings in the journal Science Advances.

Thermal radiation, which originates from random fluctuations in materials, is traditionally considered an incoherent signal. Most conventional thermal emitters show weak to zero circular polarization in the emitted heat. Surprisingly, the thermal radiation reaching the earth from many astronomical objects possesses significant circular polarization. This intriguing phenomenon leads to the discovery of strong magnetic fields in some condensed stars, offers explanations of puzzles about the early universe, and even provides a possible signature of life.

“Spinning thermal radiation is extremely rare in nature and is only found in some condensed stars,” says Jacob. 

“Our work provides a new way to generate this type of radiation, which has potential in a variety of applications, including thermal imaging and communication.”

The researchers discovered that by using a metasurface made up of an array of F-shaped structures, they were able to generate predominantly left-handed circularly polarized thermal radiation in all directions, resulting in non-vanishing optical helicity for the first time. The team reached 39% of the fundamental limit in optical helicity with their design and also showed that the characteristics of emitted thermal photons can be tailored by the symmetries of the metasurface, demonstrating effective control over thermal radiation in its various properties.