標題: Designable Spectrometer-Free Index Sensing Using Plasmonic Doppler Gratings
作者: Lin, Fan-Cheng
See, Kel-Meng
Ouyang, Lei
Huang, You-Xin
Chen, Yi-Ju
Popp, Jurgen
Huang, Jer-Shing
電子物理學系
Department of Electrophysics
公開日期: 6-Aug-2019
摘要: Typical nanoparticle-based plasmonic index sensors detect the spectral shift of localized surface plasmon resonance (LSPR) upon the change of the environmental index. Therefore, they require broadband illumination and spectrometers. The sensitivity and flexibility of nanoparticle-based index sensors are usually limited because LSPR peaks are usually broad and the spectral position cannot be freely designed. Here, we present a fully designable index sensing platform using plasmonic Doppler gratings (PDGs), which provide broadband and azimuthal angle dependent grating periodicity. Different from LSPR sensors, PDG index sensors are based on the momentum matching between photons and surface plasmons via the lattice momentum of the grating. Therefore, the index change is translated into the variation of the in-plane azimuthal angle for photon-to-plasmon coupling, which manifests as directly observable dark bands in the reflection image. The PDG can be freely designed to optimally match the range of index variation for specific applications. In this work, we demonstrate PDG index sensors for large (n = 1.00-1.52) and small index variations (n = 1.3330-1.3650). The tiny and nonlinear index change of the water-ethanol mixture has been clearly observed and accurately quantified. Since the PDG is a dispersive device, it enables on-site and single-color index sensing without a spectrometer and provides a promising spectroscopic platform for on-chip analytical applications.
URI: http://dx.doi.org/10.1021/acs.analchem.9b02662
http://hdl.handle.net/11536/152611
ISSN: 0003-2700
DOI: 10.1021/acs.analchem.9b02662
期刊: ANALYTICAL CHEMISTRY
Volume: 91
Issue: 15
起始頁: 9382
結束頁: 9387
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