Paper-Thin Metasurface Chip Converts Infrared Light to Visible, Enabling Novel Era of Photonics

A new ultra-thin chip developed by researchers at the Advanced Science Research Center at the CUNY Graduate Center (CUNY ASRC) can convert invisible infrared light into visible light and steer the resulting beam with precision—all without any moving parts. This breakthrough paves the way for smaller, more efficient light sources and beam-steering systems crucial for technologies like LiDAR, quantum computing, and optical communications.

How the Ultra-Thin Metasurface Chip Works

The innovative metasurface is constructed from an ultra-thin chip patterned with microscopic structures smaller than the wavelength of light. When illuminated by an infrared laser, the chip transforms the incoming light to a higher frequency, emitting a narrow, steerable beam. In experiments, the team successfully converted infrared light around 1530 nanometers—a wavelength commonly used in fiber-optic communications—into visible green light near 510 nanometers, directing it to specific angles.

“Think of it as a flat, microscopic spotlight that not only changes the color of light but also points the beam wherever you wish, all on a single chip,” said Andrea Alù, founding director of the CUNY ASRC Photonics Initiative and Distinguished Professor at the CUNY Graduate Center. [1] “By making different parts of the surface perform together, we receive both very efficient conversion of light and precise control over where that light goes.”

Overcoming a Longstanding Metasurface Tradeoff

Metasurfaces have been used for years to manipulate light, but traditionally faced a tradeoff between efficiency, and control. Structures offering precise control often lacked efficiency in boosting light, while highly efficient structures sacrificed fine control over the beam shape. [2]

The CUNY ASRC device overcomes this limitation by combining both advantages for nonlinear light generation—the process of converting one color of light into another. It utilizes a collective resonance, known as a quasi–bound state in the continuum, to trap and amplify the incoming infrared light across the entire surface. Simultaneously, each tiny element on the metasurface is rotated according to a carefully designed pattern, creating a position-dependent phase shift that functions like a built-in lens or prism.

Generating and Steering Third Harmonic Light

This unique structure enables the chip to produce third-harmonic light—light with a frequency three times that of the incoming beam—while simultaneously steering the resulting beam. Reversing the polarization of the incoming light reverses the direction of the outgoing beam, providing a simple and effective beam-steering mechanism. [3] The system achieves a third harmonic signal approximately 100 times more efficient than comparable beam-shaping devices lacking these collective resonances.

Toward Compact Light Sources and On-Chip Photonics

The ability to efficiently generate and guide new colors of light using a flat chip has significant implications for future technologies. “This platform opens a path to ultra-compact light sources and beam-steering elements for technologies like LiDAR, quantum light generation, and optical signal processing, all integrated directly on a chip,” said Michele Cotrufo, a former postdoctoral fellow at CUNY and now an assistant professor at the University of Rochester. [1]

Researchers suggest that future iterations of the technology could involve stacking or combining multiple metasurfaces, each tuned to a slightly different wavelength, to broaden the system’s operational range. [4]

Reference: Cotrufo, M., Carletti, L., Overvig, A., & Alù, A. (2026). Nonlinear nonlocal metasurfaces. ELight, 10.1186/s43593-025-00116-7

The work was supported by the U.S. Department of Defense, the Simons Foundation, and the European Research Council.