Super-Dispersive Off-Axis Meta-Lenses for Compact High Resolution Spectroscopy.
Metasurfaces have opened a new frontier in the miniaturization of optical technology by allowing exceptional control over the wavefront. Here, we demonstrate off-axis meta-lenses that simultaneously focus and disperse light of different wavelengths with unprecedented spectral resolution. They are designed based on the geometric phase via rotated silicon nanofins and can focus light at angles as large as 80°. Due to the large angle focusing, these meta-lenses have superdispersive characteristics (0.27 nm/mrad) that make them capable of resolving wavelength differences as small as 200 pm in the telecom region. In addition, by stitching several meta-lenses together, we maintain a high spectral resolution for a wider wavelength range. The meta-lenses have measured efficiencies as high as 90% in the wavelength range of 1.1 to 1.6 μm. The planar and compact configuration together with high spectral resolution of these meta-lenses has significant potential for emerging portable/wearable optics technology.
Harvard John A. Paulson School of Engineering and Applied Sciences, Harvard University , Cambridge, Massachusetts 02138, United States.
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M
Khorasaninejad
Harvard John A. Paulson School of Engineering and Applied Sciences, Harvard University , Cambridge, Massachusetts 02138, United States.
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WT
Chen
Harvard John A. Paulson School of Engineering and Applied Sciences, Harvard University , Cambridge, Massachusetts 02138, United States.|University of Waterloo , Waterloo, Ontario N2L 3G1, Canada.
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J
Oh
Harvard John A. Paulson School of Engineering and Applied Sciences, Harvard University , Cambridge, Massachusetts 02138, United States.
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F
Capasso
Metasurface; off-axis meta-lens; spectroscopy; superdispersive elements