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Proceedings Paper

Mid-infrared high-efficiency plasmonic flat lens (Conference Presentation)
Author(s): Alireza Safaei; Michael N. Leuenberger; Debashis Chanda

Paper Abstract

Conventional optical elements such as lenses, waveplates and polarizers function by adding phase delays to the propagating light. The thicknesses of these dielectric optical components are much larger than wavelength to accumulate 0-π phase shift. Moreover, spherical aberration and diffraction limit restrict their usage in integrated photonics circuits. Metasurface based lenses change the phase of transmitted and reflected electromagnetic waves significantly at resonance by exciting surface plasmons on the metallic arrays with thickness much lower than the wavelength of the incident light. However, previous demonstrations of plasmonic lens suffer from low transmission efficiency (< 20%) due to the high plasmonic losses. We overcame this shortcoming to some extend by engineering plasmonic coupling and demonstrated a relatively high 75% transmission in the mid infrared spectral domain. In this proposed work, coupled one dimensional array of gold disks with variable diameters have been employed to add varying phases to the transmitted light in order to create the phase front curvature in mid-IR wavelength range needed for the focusing of the incident radiation. The designed nanostructured surface achieves a resolution beyond the diffraction limit in thin-film planar geometry. The focal point, resolution and transmission efficiency can be tuned by various parameters such as period, diameters, and the size of the disks. The confocal measurement method has been performed to measure the far field focal volume of the fabricated lens, which is in good agreement with the theoretical results. Thin-film planar layout and subwavelength resolution mitigate the limitations of conventional optical elements.

Paper Details

Date Published: 28 April 2017
PDF: 1 pages
Proc. SPIE 10112, Photonic and Phononic Properties of Engineered Nanostructures VII, 101120P (28 April 2017); doi: 10.1117/12.2256304
Show Author Affiliations
Alireza Safaei, Univ. of Central Florida (United States)
Michael N. Leuenberger, Univ. of Central Florida (United States)
Debashis Chanda, Univ. of Central Florida (United States)

Published in SPIE Proceedings Vol. 10112:
Photonic and Phononic Properties of Engineered Nanostructures VII
Ali Adibi; Shawn-Yu Lin; Axel Scherer, Editor(s)

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