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Biosensing with the singular phase of an ultrathin metal-dielectric nanophotonic cavity.

ABSTRACT: The concept of point of darkness has received much attention for biosensing based on phase-sensitive detection and perfect absorption of light. The maximum phase change is possible at the point of darkness where the reflection is almost zero. To date, this has been experimentally realized using different material systems through the concept of topological darkness. However, complex nanopatterning techniques are required to realize topological darkness. Here, we report an approach to realize perfect absorption and extreme phase singularity using a simple metal-dielectric multilayer thin-film stack. The multilayer stack works on the principle of an asymmetric Fabry-Perot cavity and shows an abrupt phase change at the reflectionless point due to the presence of a highly absorbing ultrathin film of germanium in the stack. In the proof-of-concept phase-sensitive biosensing experiments, we functionalize the film surface with an ultrathin layer of biotin-thiol to capture streptavidin at a low concentration of 1?pM.

SUBMITTER: Sreekanth KV

PROVIDER: S-EPMC5785542 | biostudies-literature | 2018 Jan

REPOSITORIES: biostudies-literature

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Biosensing with the singular phase of an ultrathin metal-dielectric nanophotonic cavity.

Sreekanth Kandammathe Valiyaveedu KV Sreejith Sivaramapanicker S Han Song S Mishra Amita A Chen Xiaoxuan X Sun Handong H Lim Chwee Teck CT Singh Ranjan R

Nature communications 20180125 1

The concept of point of darkness has received much attention for biosensing based on phase-sensitive detection and perfect absorption of light. The maximum phase change is possible at the point of darkness where the reflection is almost zero. To date, this has been experimentally realized using different material systems through the concept of topological darkness. However, complex nanopatterning techniques are required to realize topological darkness. Here, we report an approach to realize perf ...[more]

PMID: 29371614

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Project description:We describe a hybrid metal-dielectric waveguide structures (MDWs) with numerous potential applications in the biosciences. These structures consist of a thin metal film coated with a dielectric layer. Depending on the thickness of the dielectric layer, the modes can be localized near the metal, within the dielectric, or at the top surface of the dielectric. The optical modes in a metal-dielectric waveguide can have either S (TE) or P (TM) polarization. The dielectric spacer avoids the quenching, which usually occurs for fluorophores within about 5 nm from the metal. Additionally, the resonances display a sharp angular dependence and can exhibit several hundred-fold increases in intensity (E2) at the silica-air interface relative to the incident intensity. Fluorophores placed on top of the silica layer couple efficiently with the metal, resulting in a sharp angular distribution of emission through the metal and down from the bottom of the structure. This coupling occurs over large distances to several hundred nm away from the metal and was found to be consistent with simulations of the reflectivity of the metal-dielectric waveguides. Remarkably, for some silica thicknesses, the emission is almost completely coupled through the structure with little free-space emission away from the metal-dielectric waveguide. The efficiency of fluorophore coupling is related to the quality of the resonant modes sustained by the metal-dielectric waveguide, resulting in coupling of most of the emission through the metal into the underlying glass substrates. Metal-dielectric waveguides also provide a method to resolve the emission from surface-bound fluorophores from the bulk-phase fluorophores. Metal-dielectric waveguides are simple to fabricate for large surface areas, the resonance wavelength can be adjusted by the dielectric thickness, and the silica surface is suitable for coupling to biomolecules. Metal-dielectric waveguides can have numerous applications in diagnostics and high-throughput proteomics or DNA analysis.

Dataset Information

Biosensing with the singular phase of an ultrathin metal-dielectric nanophotonic cavity.

Publications

Biosensing with the singular phase of an ultrathin metal-dielectric nanophotonic cavity.

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