Anti-Resonant Reflecting Optical Waveguides (ARROWS) as Optimal Optical Detectors for μTAS Applications

Abstract

Anti-Resonant Reflecting Optical Waveguides (ARROW) have been developed for integrated optical devices, as they permit waveguiding in low-index layers fabricated from materials such as silicon dioxide. They have been developed mainly for integrated optics applications, as they are compatible with standard silicon processing techniques [1,2]. The main feature of ARROW waveguides is that light confinement is by Fabry-Perot anti-resonant reflectors, rather than total internal reflection (TIR). As a result of the light confinement mechanism, ARROWs can be constructed such that the light is confined in a low refractive index medium surrounded by high refractive index reflecting boundaries. ARROWs have been proposed as optical sensorsARROWs are extremely well suited to μTAS applications, since they permit waveguiding in a low index medium such as an aqueous solution. A simple refinement of the basic ARROW structure permits simple in- and out-coupling of light by frustrated total internal reflection (FTR), eliminating the need for complex coupling arrangements such as end-fire or grating couplers. ARROWs can be used to monitor optical absorption and refractive index, as well as to excite fluorescence.KeywordsOptical waveguide sensorsfluorescencerefractive index sensing