Open AccessTerahertz phase contrast imaging of sorption kinetics in porous coordination polymer nanocrystals using differential optical resonator
Author(s) -
F. Blanchard,
Kenji Sumida,
Christian Wolpert,
Manuel Tsotsalas,
Tomoko Tanaka,
Akira Doi,
Susumu Kitagawa,
David G. Cooke,
Shuhei Furukawa,
Kōichiro Tanaka
Publication year - 2014
Publication title -
optics express
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.394
H-Index - 271
ISSN - 1094-4087
DOI - 10.1364/oe.22.011061
Subject(s) - resonator , materials science , terahertz radiation , absorption (acoustics) , optoelectronics , optics , phase (matter) , metamaterial , split ring resonator , physics , quantum mechanics , composite material
The enhancement of light-matter coupling when light is confined to wavelength scale volumes is useful both for studying small sample volumes and increasing the overall sensing ability. At these length scales, nonradiative interactions are of key interest to which near-field optical techniques may reveal new phenomena facilitating next-generation material functionalities and applications. Efforts to develop novel chemical or biological sensors using metamaterials have yielded innovative ideas in the optical and terahertz frequency range whereby the spatially integrated response over a resonator structure is monitored via the re-radiated or leaked light. But although terahertz waves generally exhibit distinctive response in chemical molecules or biological tissue, there is little absorption for subwavelength size sample and therefore poor image contrast. Here, we introduce a method that spatially resolves the differential near-field phase response of the entire resonator as a spectral fingerprint. By simultaneously probing two metallic ring resonators, where one loaded with the sample of interest, the differential phase response is able to resolve the presence of guest molecules (e.g. methanol) as they are adsorbed or released within the pores of a prototypical porous coordination polymer.