An international team of researchers has developed a theoretical design for a new device capable of controlling heat in ways previously thought impossible, potentially opening the door to smarter infrared sensors, advanced energy systems, and next-generation photonic memory.
The study, published in Laser & Photonics Reviews, challenges a long-standing limitation in thermal physics known as Kirchhoff’s law of thermal radiation.
The law states that a material’s ability to absorb heat must match its ability to emit heat at the same angle and wavelength, making precise control of thermal energy difficult.
Researchers from Osaka Metropolitan University and collaborating institutions have proposed a solution by designing a device called a metagrating, which uses magnetic fields to manipulate light and control heat absorption independently of heat emission.
“We made heat radiation behave in a smarter way,” said physicist Shunsuke Murai of Osaka Metropolitan University. “Achieving these capabilities in a working model could enable a new generation of efficient infrared emitters, thermal energy devices, sensors, and photonic memory technologies.”
The proposed metagrating combines a magneto-optical material, whose optical properties change under a magnetic field, with a phase-change material that stores information by switching between amorphous and crystalline states. The phase-change material, Ge₂Sb₂Te₅, is already widely used in rewritable CDs and DVDs.
The device also features microscopic grating structures that trap and direct incoming light more efficiently than previous approaches. By adjusting the angle of incoming light, the magnetic field strength, and the grating’s dimensions, researchers found they could “program” how the device absorbs heat across a broad range of wavelengths without requiring matching thermal emission.
According to the research team, the design establishes a new framework for active, nonreciprocal thermal control that could eventually support chip-scale thermal photonics.
Despite the promising findings, the work remains theoretical. The researchers relied on mathematical modeling and simulations rather than a physical prototype, and they acknowledge that further research is needed to demonstrate the concept experimentally. The study also focused primarily on heat absorption, with heat emission largely inferred rather than directly analyzed.
“Our ultimate goal is to develop compact devices that can actively control heat radiation, much like electronic circuits control the flow of electricity,” said physicist Koichi Okamoto of Osaka Metropolitan University. “Such devices could be used in smarter infrared sensors, more efficient energy systems, and new types of photonic memory that store information using light and heat instead of electrical charges.”
If successfully demonstrated in hardware, the technology could have applications in thermal management, energy harvesting, infrared imaging, optical computing, and advanced memory systems, representing a significant step toward programmable control of heat at the nanoscale.
