New geometry for planar UV written refractive index sensors

Abstract

We shall present some of our recent results from our work on UV written planar waveguide refractive index sensors. Refractive index of an analyte is measured through the perturbation of an optical mode, interrogation of the modal index is achieved via the reflected spectra from a Bragg grating defined in the same process as the channel waveguide. Here we introduce a new geometry which embraces the benefits of planar technology to realise new integrated devices. The geometry allows several different sensors to be defined on the same substrate each offering complementary information. Such information may include index as a function of penetration depth for surface binding analytes, interrogation wavelength for dispersion analysis, enhanced sensitivity in specific index ranges and temperature compensation. We shall also outline the inherent fabrication advantages and device feature benefits, including a reduction in return loss, spectral artefacts and a suggested reduction in stress induced birefringence. The silica sensing surface opposed to gold used in SPR devices opens new avenues to exploit surface binding. With a marked reduction in complexity and cost these devices may have significant impact in future sensor markets.

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Identifiers

ORCID for James C. Gates: orcid.org/0000-0001-8671-5987

ORCID for Christopher Holmes: orcid.org/0000-0001-9021-3760

ORCID for Corin B.E. Gawith: orcid.org/0000-0002-3502-3558

ORCID for Peter G.R. Smith: orcid.org/0000-0003-0319-718X

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