Low-Index-Contrast Dielectric Lattices on Metal for Refractometric Sensing

• This article reports refractometric sensing using two optical resonances of different types supported by TiO2 nanopillar arrays on a gold film, which can be exposed to aqueous or organic environments. One lattice resonance, with enhanced electric fields extending into the surrounding environment, can maintain a quality factor Q > 200 when the bulk refractive index of the surrounding environment varies in a large range from 1.33 to 1.58. This lattice resonance exhibits not only sharp transitions of reflected light intensity but also rapid phase changes. The other resonance is of plasmonic nature with electric fields localized on the metal surface. Small changes in the bulk refractive index or the adsorbate layer (thickness and index) can be detected, with sensitivity comparable to that of plasmonic counterparts. The present hybrid metal–dielectric platform is promising for applications requiring dielectric instead of metallic sensing surfaces.

Subject headings

NATURVETENSKAP  -- Fysik -- Atom- och molekylfysik och optik (hsv//swe)

NATURAL SCIENCES  -- Physical Sciences -- Atom and Molecular Physics and Optics (hsv//eng)

Keyword

Dielectric lattices

Electric fields

Lattice resonances

Low index contrast

Metals

Nano-pillar arrays

Optical resonance

Oxide minerals

Plasmonics

Quantum optics

Reflected light intensity

Refractive index

Refractometric sensing

Resonance

Surrounding environment

Titanium dioxide

hybrid metal–dielectric nanostructures

lattice resonances

sensing

surface modes

Publication and Content Type

ref (subject category)

art (subject category)