NDLI: Spatial Resolution and Refractive Index Contrast of Resonant Photonic Crystal Surfaces for Biosensing

Content Provider	IEEE Xplore Digital Library
Author	Triggs, G.J. Fischer, M. Stellinga, D. Scullion, M.G. Evans, G.J.O. Krauss, T.F.
Copyright Year	2009
Abstract	By depositing a resolution test pattern on top of a Si₃N₄ photonic crystal resonant surface, we have measured the dependence of spatial resolution on refractive index contrast Δn. Our experimental results and finite-difference time-domain (FDTD) simulations at different refractive index contrasts show that the spatial resolution of our device reduces with reduced contrast, which is an important consideration in biosensing, where the contrast may be of order 10^-2. We also compare 1-D and 2-D gratings, taking into account different incidence polarizations, leading to a better understanding of the excitation and propagation of the resonant modes in these structures, as well as how this contributes to the spatial resolution. At Δn 0.077, we observe resolutions of 2 and 6 μm parallel to and perpendicular to the grooves of a 1-D grating, respectively, and show that for polarized illumination of a 2-D grating, resolution remains asymmetrical. Illumination of a 2-D grating at 450 results in symmetric resolution. At very low index contrast, the resolution worsens dramatically, particularly for Δn <; 0.01, where we observe a resolution exceeding 10 μm for our device. In addition, we measure a reduction in the resonance linewidth as the index contrast becomes lower, corresponding to a longer resonant mode propagation length in the structure and contributing to the change in spatial resolution.
Starting Page	1
Ending Page	10
Page Count	10
File Size	1957809
File Format	PDF
ISSN	19430655
Volume Number	7
Issue Number	3
Language	English
Publisher	Institute of Electrical and Electronics Engineers, Inc. (IEEE)
Publisher Date	2015-01-01
Publisher Place	U.S.A.
Access Restriction	Subscribed
Rights Holder	Institute of Electrical and Electronics Engineers, Inc. (IEEE)
Subject Keyword	Gratings Spatial resolution Refractive index Resists Surface waves Indexes polarisation Resonant surface biosensor grating photonic crystal spatial resolution refractive index contrast polarization
Content Type	Text
Resource Type	Article
Subject	Atomic and Molecular Physics, and Optics Electrical and Electronic Engineering

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