Detection Solutions for the Characterization and Development of Metasurfaces

Metasurfaces are class of metamaterials engineered to exert explicit control over the phase, amplitude, frequency, and polarization of electromagnetic radiation from radio frequencies to visible light.¹ These surfaces are two-dimensional materials constructed from arrays of sub-wavelength size features. One interesting property of metasurfaces is that they can be constructed so their effect on light is time-varying instead of static, enabling a greater degree of control of how electromagnetic radiation is manipulated. Due to the broad frequency space for which they can be constructed, researchers are exploring their use as lenses (metalens), waveguides, reducing radar cross-sections, wavefront manipulation, and much more.²

With the compact nature of these materials, sub-micron thickness for visible to SWIR wavelengths, miniaturized imaging and optical technologies become possible. For instance, high numeric aperture metalenses³ enable the creation of small imaging systems. These could find applications on UAVs, drones, or satellites where physical space for a lens system is limited and the reduction in weight is an advantage. Additional examples relevant to security applications include the development of low form factor augmented reality displays and biological/chemical sensors using metasurfaces.⁴ Before their integration, however, these novel surfaces need to be characterized and tuned for specific applications.

We highlight some of the optical characterization tools that researchers are using to develop the next generation of metasurfaces.

While resolving the nanoscopic features of metasurfaces are best left to techniques other than optical microscopy (ex. SEM), optical microscopies can be used to characterize spatial variation in the wavefront phase⁵, imaging for nonlinear optical encryption by metasurfaces⁶, and converting NIR light into visible wavelength light for easier detection⁷. sCMOS cameras are the primary imaging technology behind these examples. This class of imaging camera possesses low read noise, fast frame rates, high quantum efficiency, and robust linearity across the full well depth of the camera. Such properties make sCMOS camera technology readily applicable to quantitative characterization of metasurface properties. InGaAs based CMOS imaging cameras are also available, extending sensitivity into the NIR and complementing the visible/UV sensitivity of silicon based sCMOS cameras. Other imaging technologies include CCD and EMCCDs, such as Oxford Instrument Andor’s iKon and iXon camera lines. These camera platforms provide excellent solutions for long exposure experiments and single photon sensitivity, respectively.

When it comes to understanding the wavelength specific properties of metasurfaces, the incorporation of a spectrograph provides the necessary dispersion of light to resolve different spectral properties. From the UV to the short-wave infrared (SWIR), Andor’s Kymera and Shamrock spectrographs enable high resolution, reproducible, and precise spectroscopy experiments. The Czerny-Turner design of these spectrographs enable a truly modular experience with a wide array of coupling input options, multiple input/output chasses, and up to four grating turrets in a single spectrograph. An additional echelle style spectrograph enables high resolution spectra to be recorded across a large spectral window in a single shot. These spectrographs are already being used to characterize the spectral properties of vertically stacked metalenses⁸, study the high-harmonic generation of metasurfaces irradiated by mid-wave infrared light⁹, and enable the development of nonlinear nanophotonic elements¹⁰.

General Outlook

Metasurfaces, and in particular metalenses, are a material class that hold the potential to deliver novel solutions in the development of small imaging systems, upconversion modules for efficient detection of NIR or SWIR radiation, advanced coatings for camouflage applications, and more. Oxford Instrument Andor’s catalogue of camera and spectrograph technology provide the necessary optical tools for effective spectral and imaging characterization of the emission, diffraction, and transmission/reflection of light from metasurfaces.

References

1. V. Kildishev, A. Boltasseva, V.M. Shalaev, Planar Photonics with Metasurfaces, Science, 2013, 339 (6125), 1232009

2. I. Kuznetsov, et al., Roadmap for Optical Metasurfaces, ACS Photonics, 2024, 11 (3), 816-865

3. Paniagua-Dominguez, et al., A Metalens with Near-Unity Numerical Aperture, Nano Letters, 2018, 18 (3), 2124-2132

4. Yang, et al., Integrated metasurfaces for re-envisioning a near-future disruptive optical platform, Light: Science & Applications, 2023, 12, 152

5. Khadir, et al., Metasurface Optical Characterization Using Quadriwave Lateral Shearing Interferometry, ACS Photonics, 2021, 8 (2), 603-613

6. Walter, G. Li, C. Meier, S. Zhang, T. Zentgraf, Ultrathin Nonlinear Metasurface for Optical Image Encoding, Nano Letters, 2017, 17 (5), 3171-3175

7. Schlickriede, N. Waterman, B. Reineke, P. Georgi, G. Li, S. Zhang, T. Zentgraf, Imaging through Nonlinear Metalens Using Second Harmonic Generation, Advanced Materials, 2018, 30, 1703843

8. Avayu, E. Almeida, Y. Prior, T. Ellenbogen, Composite functional metasurfaces for multispectral achormatic optics, Nature Communications, 2017, 8, 14992

9. Zograf, et al., High-Harmonic Generation from Resonant Dielectric Metasurfaces Empowered by Bound States in the Continuum, ACS Photonics, 2022, 9 (2), 567-574

10. Zograf et al., Ultrathin 3R-MoS₂ metasurfaces with atomically precise edges for efficient nonlinear nanophotonics, Communications Physics, 2025, 8, 271