A chip controls infrared light one pixel at a time, helping cameras detect heat, gases, and chemicals for imaging, monitoring, and computing uses.
Researchers at MIT have developed a chip-based optical device that can control infrared light at the level of individual pixels, making it possible to build smaller and more flexible infrared imaging systems. The device acts as a tunable lens whose microscopic pixels can independently adjust how they interact with incoming infrared light, allowing cameras to change focus and detect different signals without using moving parts.
The device is based on a metasurface—a flat optical structure with tiny engineered patterns that control light. Unlike earlier metasurfaces, which could only change their optical properties across the entire surface at once, the new design allows each pixel to be controlled independently.
To achieve this, the researchers used a crossbar architecture similar to those found in display technologies. Two layers of copper wires are arranged perpendicular to each other, with a doped silicon layer beneath them. At each wire intersection, the silicon generates heat that changes the phase of a special material between crystalline and amorphous states. This alters how each pixel interacts with infrared light. A built-in diode at every pixel helps prevent unwanted electrical currents from affecting neighboring pixels.
According to the researchers, the crossbar design can potentially support millions of individually controlled pixels while avoiding current leakage, making it suitable for large-scale active metasurfaces.
The team fabricated a 6×6 pixel metasurface array using facilities at MIT.nano and a commercial semiconductor chip foundry. Tests showed the pixels could switch repeatedly and operate reliably over many cycles.
The researchers believe using standard chip manufacturing techniques will make it easier to scale the technology beyond the laboratory. They are now working to increase the number of pixels and improve the device so it can capture more detailed infrared information.
Potential applications include thermal imaging, gas and chemical detection, environmental monitoring, space observation, defense systems such as night vision, and optical computing. Because many organic molecules absorb mid-infrared light, the device could also help detect gases such as methane and propane.
The researchers also see future potential for the technology in optical computing, where programmable metasurfaces could perform parts of AI calculations by processing information directly with light instead of conventional electronic circuits.
