title: Near-field examination of perovskite-based superlenses and superlens-enhanced probe-object coupling.
abstract: A planar slab of negative-index material works as a superlens with sub-diffraction-limited resolution, as propagating waves are focused and, moreover, evanescent waves are reconstructed in the image plane. Here we demonstrate a superlens for electric evanescent fields with low losses using perovskites in the mid-infrared regime. The combination of near-field microscopy with a tunable free-electron laser allows us to address precisely the polariton modes, which are critical for super-resolution imaging. We spectrally study the lateral and vertical distributions of evanescent waves around the image plane of such a lens, and achieve imaging resolution of λ/14 at the superlensing wavelength. Interestingly, at certain distances between the probe and sample surface, we observe a maximum of these evanescent fields. Comparisons with numerical simulations indicate that this maximum originates from an enhanced coupling between probe and object, which might be applicable for multifunctional circuits, infrared spectroscopy and thermal sensors.
authors.affiliation: Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA. sck21@st-andrews.ac.uk
authors.forename: S C
authors.initials: SC
authors.lastname: Kehr
authors.forename: Y M
authors.initials: YM
authors.lastname: Liu
authors.forename: L W
authors.initials: LW
authors.lastname: Martin
authors.forename: P
authors.initials: P
authors.lastname: Yu
authors.forename: M
authors.initials: M
authors.lastname: Gajek
authors.forename: S-Y
authors.initials: SY
authors.lastname: Yang
authors.forename: C-H
authors.initials: CH
authors.lastname: Yang
authors.forename: M T
authors.initials: MT
authors.lastname: Wenzel
authors.forename: R
authors.initials: R
authors.lastname: Jacob
authors.forename: H-G
authors.initials: HG
authors.lastname: von Ribbeck
authors.forename: M
authors.initials: M
authors.lastname: Helm
authors.forename: X
authors.initials: X
authors.lastname: Zhang
authors.forename: L M
authors.initials: LM
authors.lastname: Eng
authors.forename: R
authors.initials: R
authors.lastname: Ramesh
mesh_terms: D017610:Calcium Compounds; D003198:Computer Simulation; D004560:Electricity; D007909:Lenses; D057054:Molecular Imaging / Q000295:instrumentation / Q000379:methods*; D010087:Oxides; D013055:Spectrophotometry, Infrared / Q000379:methods; D014025:Titanium
chemical_list: D017610:Calcium Compounds; D010087:Oxides; C059910:perovskite; D014025:Titanium