Resonant absorption of a chemically sensitive layer based on waveguide gratings

Abstract

A colorimetric sensor providing a direct visual indication of chemical contamination was developed. The sensor is a combination of a chemically sensitive dye layer and a resonant waveguide grating. Enhancement of the light absorption by the photonic structure can be clearly seen. The detection is based on the color change of the reflected light after exposure to a gas or a liquid. Low-cost fabrication and compatibility with environments where electricity cannot be used make this device very attractive for applications in hospitals, industries, with explosives, and in traffic.

Recent Advances in Resonant Waveguide Gratings

“…Visual chemical sensors based on resonant absorption conditions of RWGs have been developed to create low‐cost gas and fully passive detectors with significantly improved color change compared to thin dye‐containing films. They can be used to monitor gas contamination in public places in case of terrorist attack, gas leakages in possible explosive environments, air pollution as well as the vibrational absorption of molecules …”

“…[132,133] Another widely used implementation is hot-embossing based on a negative replication stamp made of nickel and various additives. For high-throughput replication of grating patterns, sheet to sheet and preferably roll-to-roll NIL or injection molding [134] techniques have been industrially applied, [130,135] especially for biosensing, [136] optical security, [137] and solar cell applications. [138] In order to improve the replication fidelity and to broaden the range of geometries and aspect ratios that can be replicated, UV reticulation of liquid, gel, or soft materials (UV-NIL) is preferred to hot-embossing techniques and Reproduced with permission.…”

“…They can be used to monitor gas contamination in public places in case of terrorist attack, gas leakages in possible explosive environments, air pollution as well as the vibrational absorption of molecules. [136,260]…”

Fano resonance and tunability of optical response in double-sided dielectric gratings

“…The disadvantage of grating-based sensors is that the light beam is incident through the sample solution usually, which may give some inaccuracies if the sample is absorptive [29][30][31]. In our proposal, the light is incident on the bottom grating, that does not have any interaction with an external medium (gas or liquid) filled in the gap and surface region of top grating, as shown in the inlet in Fig.…”

Waveguide-metal–dielectric bi-layer gratings for reflective filtering and color security

“…Some SWG structures as colorimetric sensors and reflective displays have also been investigated. Davoine et al [8] developed a visual sensor composed of a dye layer and a waveguide grating for providing visual indications of chemical contamination. Uddin and Magnusson [9] fabricated a highly efficient dielectric guided-mode resonant (GMR) array of filters for reflective display.…”