Imagine a tiny, flat device that can transform invisible infrared light into vibrant, visible colors and precisely direct it wherever you want—all without any moving parts. Sounds like science fiction, right? But it’s real, and it’s here. Researchers at the Advanced Science Research Center (ASRC) at CUNY Graduate Center have achieved a groundbreaking feat in photonics, creating a metasurface that could revolutionize technologies like lidar, quantum light generation, and optical signal processing. And this is the part most people miss: it does all this on a single, microscopic chip.
Published in eLight (https://link.springer.com/article/10.1186/s43593-025-00116-7), this innovation tackles a long-standing challenge in metasurface design. Traditional metasurfaces excel at either shaping light waves efficiently or controlling them precisely—but rarely both. Here’s where it gets controversial: CUNY’s device claims to do both simultaneously, combining the best of both worlds for nonlinear light generation. How? By leveraging a unique geometric design and collective resonance, it traps and amplifies infrared light while steering the output beam with pinpoint accuracy.
Here’s how it works: Each unit cell of the metasurface consists of two rectangular apertures rotated 90 degrees relative to each other. When infrared light hits the surface, nonlocal effects trigger third-harmonic generation, converting the light’s wavelength and changing its color. But that’s not all—a circularly polarized pump light excites the surface from below, allowing the direction of the emitted light to be controlled. In trials, the device transformed 1530-nanometer infrared light into visible green light (around 510 nanometers) and steered it to specific angles.
Andrea Alù, founding director of the CUNY ASRC Photonics Initiative (https://asrc.gc.cuny.edu/photonics/), puts it simply: ‘Think of it as a microscopic spotlight that changes color and direction on demand, all on a single chip. By coordinating different parts of the surface, we achieve both efficient light conversion and precise beam control.’ This dual capability could be a game-changer for compact, integrated photonic systems.
But here’s where it gets even more intriguing: The design isn’t tied to a specific material. This means it can be adapted to other nonlinear materials and wavelengths, including ultraviolet light. Michele Cotrufo from CUNY highlights its versatility: ‘Because it’s geometry-driven, the concept opens doors for ultra-compact light sources and beam-steering elements across various applications.’
However, not everyone is convinced. Some experts argue that scaling this technology for real-world applications could face challenges, such as maintaining efficiency at larger scales or integrating it with existing systems. What do you think? Is this the future of photonics, or just a promising lab experiment? Let us know in the comments—we’d love to hear your take on this potentially transformative innovation.
