Setting Up and Assessing a New Micro-Structured Waveguiding Fluorescent Architecture on Glass Entirely Elaborated by Sol-Gel Processing.

Morgane Bonnel,Michel Langlet,Davide Bucci,Ibtihel Marzouk,Alain Morand,David Riassetto

doi:10.3390/ma15030979

Abstract

Channel waveguides with diffraction gratings at their input and output for light injection and extraction, respectively, are extensively exploited for optical and photonic applications. In this paper, we report for the first time on such an architecture on glass entirely elaborated by sol–gel processing using a titanium-oxide-based photoresist that can be imprinted through a single photolithography step. This work is more particularly focused on a fluorescent architecture including channel waveguides doped with a ruthenium-complex fluorophore (tris(4,7-diphenyl-1,10-phenanthroline)ruthenium(II), Rudpp). The study demonstrates that this original sol–gel micro-structured architecture is well adapted to efficient channel waveguide/diffraction grating coupling and propagation of the fluorescence excitation and emission signals in the core of the channel waveguide. It demonstrates, in particular, a relatively large tolerance of several degrees in the angular injection fiber positioning and an important axial and vertical fiber spatial positioning tolerance of more than 100 µm at the Rudpp emission wavelength. The measurements also indicate that, in the conditions tested in this work, a Rudpp concentration of around 0.1 mM and a channel waveguide length of 2 to 5 mm offer the best trade-off in terms of excitation signal propagation and emission signal detection. This work constitutes a promising preliminary step toward the integration of our architecture into a microfluidic platform for fluorescence measurement in a liquid medium and waveguiding configuration.

Highlights

In past years, miniaturized components in the form of integrated planar or channel waveguides have largely been exploited for optical and photonic applications
The uniform diffraction effects components of this architecture, smooth and linear patterns were obtained, and a cleanillustrated in the inset of Figure 3b show that the grating was homogeneously imprinted over interface is depicted in Figure 3a between the bare channel waveguide and the area where the whole 0.5 × 1 cm2 mask area, where transparent stripes of 1 μm/2 μm width/pitch the diffraction grating was imprinted
We considered a of 17 configuration where light propagating in the core of a channel waveguide was10 extracted toward the external medium through the diffraction grating

Summary

Introduction

In past years, miniaturized components in the form of integrated planar or channel waveguides have largely been exploited for optical and photonic applications. These structures rely on the well-known principle of light confinement. In planar or channel waveguide configurations, the presence of a target analyte in the surrounding medium induces changes in optical properties (absorption coefficient, refractive index, fluorescence intensity, plasmon resonance, etc.) at the waveguide surface. This in turn modifies the signal propagating along the waveguide core.

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Conclusion