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Proceedings Paper

Deep-subwavelength near-field imaging based on perovskites and doped semiconductors at infrared frequencies
Author(s): Yongmin Liu
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Paper Abstract

A superlens that can create sub-diffraction-limited imaging has attracted extensive interest over the past decade. In this paper, we discuss our recent work of infrared superlenses based on perovskites and doped semiconductors. Perovskite oxides show pronounced phonon resonances in the range of 10 to 30 μm, giving rise to negative permittivities around the resonant frequencies. Consequently, we can match a pair of perovskite materials with permittivities in opposite signs to fulfill the superlensing condition. Using a scattering-type scanning near-field optical microscope (s-SNOM) coupled with a tunable free-electron laser, we investigate the evanescent waves in the image plane of perovskite superlenses to address precisely the surface polariton modes, which are important to enhance imaging resolution. Sub-diffractionlimited images with resolution of λ/14 have been achieved at the superlensing wavelength. We also demonstrate a nearfield superlens based on doped semiconductors in the mid-infrared region. Highly doped n-GaAs induces a resonant enhancement of evanescent waves, leading to a significantly improved spatial resolution at the wavelength around 20 μm that is adjustable by changing the doping level. Experimentally, gold stripes below the GaAs superlens are imaged with a λ/6 subwavelength resolution by s-SNOM. Full-wave simulation results are in very good agreement with the observed superlensing effect. These results promise a wide range of applications for infrared imaging, spectroscopy and biochemical sensing at the nanoscale.

Paper Details

Date Published: 18 May 2017
PDF: 7 pages
Proc. SPIE 10194, Micro- and Nanotechnology Sensors, Systems, and Applications IX, 101940K (18 May 2017); doi: 10.1117/12.2257236
Show Author Affiliations
Yongmin Liu, Northeastern Univ. (United States)

Published in SPIE Proceedings Vol. 10194:
Micro- and Nanotechnology Sensors, Systems, and Applications IX
Thomas George; Achyut K. Dutta; M. Saif Islam, Editor(s)

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