Metalens-based spectrometer fits on a chip
A new optical spectrometer is super-compact thanks to a metalens that focuses light at multiple wavelengths
The new device can detect light spectra with a resolution of 1 nm, and unlike its bulkier predecessors, it could be integrated onto a chip, with potential applications in security and information processing – Isabelle Dumé in Physicsworld
From the report:
Researchers led by Xianzhong Chen from the Institute of Photonics and Quantum Sciences at Herriot-Watt University, UK, have now developed a compact spectrometer that can detect light spectra with a resolution of 1 nm over a broad range of wavelengths. It accomplishes this feat thanks to a planar nanostructure called an optical metasurface that can manipulate the amplitude, phase and polarization of incident light on a subwavelength scale.
The metasurface in the Herriot-Watt device consists of gold nanorods that are patterned atop an indium tin oxide-coated silicon dioxide substrate using standard electron beam lithography and lift-off processes. An individual device measures just 300 µm x 300 µm, and Chen explains that it is based on a novel lens design that accurately maps the wavelengths of an incident light beam to different positions on the flat focal plane of the lens. Using this design, it is possible to split and focus light with high-resolution control over its dispersion.
According to the researchers, who describe the new metalens spectrometer in Light Science & Applications, the compact and ultrathin nature of their device mean that it could be used in on-chip integrated photonics where spectral analysis and information are processed in a compact platform.
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