The work, published in Light: Science & Applications, was led by Roy Maman, a PhD student in the research group of Professor Uriel Levy, working alongside Professor Ilya Goykhman and nanofabrication specialist Noa Mazurski. Their platform is a dual-band metasurface, an engineered array of subwavelength structures that controls how thermal radiation leaves a surface. The central achievement is spectral decoupling. Conventional thermal photonics struggle to manipulate the mid-wave and long-wave bands independently at the pixel level, because the physics that governs emission in one range tends to drag the other along with it. The Jerusalem team broke that dependency using a carefully designed metal-insulator-metal architecture in which each unit cell behaves like a pair of coupled resonators, one tuned to each atmospheric window.

Each pixel of the metasurface is built from a stack in which patterned nanodisks sit above a thin dielectric spacer and a metallic backplane. This metal-insulator-metal configuration supports resonant modes that absorb and re-emit thermal radiation at selectable wavelengths. By adjusting geometric parameters such as the radius of the nanodisks and the periodicity of the array, the designers can move the resonance peak of each band and reshape its spectral width. Kirchhoff’s law of thermal radiation ties a material’s emissivity to its absorptivity, so sculpting the absorption spectrum directly sculpts the thermal emission spectrum. A pixel engineered to emit strongly in the mid-wave band but weakly in the long-wave band will glow brightly to a mid-wave camera while appearing dark to a long-wave camera, and the reverse configuration is equally available.

Getting two independent channels out of one physical structure is a delicate optimization problem, because the geometric degrees of freedom are shared between the resonances. The researchers approached it with a mathematical stability analysis rooted in control theory, mapping how each geometric parameter influences each resonance property and selecting operating points where the cross-sensitivities vanish. The team summarized the principle behind the design: using a mathematical stability analysis rooted in control theory, they leveraged fundamental geometric degrees of freedom to independently tune optical resonances across both wavelength bands simultaneously, decoupling control over key resonance parameters such as peak position and spectral width and achieving near-zero correlation between the two distinct infrared channels. In practical terms, a grayscale value written into a pixel for the mid-wave image has no measurable effect on the grayscale value the same pixel presents in the long-wave image.

The demonstration that turns this physics into something visually striking is a two-portrait encryption experiment on a single chip. The researchers encoded two completely different detailed images into the exact same pixel area. Viewed through a mid-wave infrared camera, the chip displays a grayscale portrait of Sir Isaac Newton. Viewed through a long-wave infrared camera, the identical chip reveals the face of Gottfried Wilhelm Leibniz, Newton’s historical rival in the calculus priority dispute. The choice of subjects is a fitting metaphor for the technology itself: one surface, two irreconcilable truths, and the answer depends entirely on which window the observer chooses to look through.

Encryption is only one of two headline applications. In an alternate configuration, the same platform can be programmed for thermal camouflage, projecting identical signatures in both bands so that an object blends seamlessly into an engineered background. This matters because dual-band sensors are specifically deployed to defeat single-band spoofing; a hot spot that looks like the ambient scene in one window but betrays itself in the other is a classic failure mode of conventional camouflage. By matching emissivity patterns across both atmospheric windows simultaneously, the metasurface addresses the multi-band detection strategy at its own level rather than tricking one sensor at a time.

Robustness is where the platform separates itself from laboratory curiosities. The encoded images remain clear and stable across wide viewing angles and over a broad temperature range, which means the hidden information does not degrade when the chip is heated or when the camera moves off-axis. In the reported measurements, thermal images were captured at chip temperatures ranging from 32 degrees Celsius to 112 degrees Celsius, and at observation angles from zero degrees up to 44 degrees. As the chip temperature rises, the encoded patterns grow increasingly dominant over the background thermal emission, sharpening the images rather than washing them out. The long-wave image in particular stays remarkably stable at every measured angle and temperature, while the mid-wave image remains distinguishable and clearly distinct from its long-wave counterpart, confirming that high-frequency visual data never leaks between the two channels.

The physical mechanism behind this stability lies in the resonant nature of the emission control. Because the emissivity is set by geometry rather than by temperature-dependent material properties, the spectral fingerprints of the pixels persist as the chip heats and cools. Angular stability follows from the subwavelength scale of the unit cells, which suppresses the diffraction effects that would otherwise scatter or shift the response as the viewing angle changes. This combination of thermal and angular tolerance is what makes the platform a candidate for real-world deployment rather than a fixed-conditions demonstration, since field sensors rarely enjoy the luxury of a fixed camera position or a constant target temperature.

Manufacturing considerations strengthen the case further. The design is fully compatible with standard photolithography, the workhorse patterning process of the semiconductor industry, so the metasurfaces can be scaled to large areas at low unit cost without exotic fabrication steps. That compatibility matters for the security applications the researchers envision, where anti-counterfeiting tags and encryption elements are only useful if they can be produced cheaply and in volume. The team forecasts that the platform could redefine next-generation anti-counterfeiting tags, secure optical data encryption, and multi-sensor military stealth, positioning the chip at the intersection of commercial authentication technology and defense-grade signature management.

The researchers also point toward a dynamic future for the technology. Incorporating active materials such as graphene, electro-optic layers, or phase-change alloys could eventually unlock real-time, reconfigurable dual-band thermal animations, effectively turning static camouflage into dynamic, adaptable thermal displays. In such a scheme, the two portraits hidden in a single surface would no longer be fixed at fabrication time but could be rewritten electrically or thermally, allowing a camouflaged object to update its false signature on demand or an encryption element to cycle through authentication states. For now, the passive version already delivers something previously out of reach: two uncorrelated thermal images coexisting on one chip, each invisible to the camera assigned to the other, built with the same fabrication tools that already produce the world’s microelectronics.

Subject of Research: Dual-band metasurfaces for independent emissivity control in mid-wave and long-wave infrared imaging

Article Title: Multi-channel metasurface reshapes thermal camouflage and security encryption

Article References: Multi-channel metasurface reshapes thermal camouflage and security encryption. (n.d.). Original publication

Image Credits: AI Generated

DOI: Not provided

Keywords: metasurface, thermal camouflage, infrared imaging, MWIR, LWIR, emissivity control, optical encryption, anti-counterfeiting, photolithography, thermal photonics, nanofabrication, Light Science and Applications