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Free keywords:
fibre optic microsensor; tapered fibre; refractive index; surface plasmon resonance
Abstract:
We have developed a fibre-optic microsensor for refractive index measurements and used it with a biological application. It is targeting a refractive index range for aqueous environments between 1.30 and 1.36 and a spatial resolution of below 1 mm. The sensing element consists of a single-ended tapered optical fibre that is coated with a 50 nm gold layer. White light is coupled into the fibre and excites surface plasmon resonance (SPR) at the fibre tip. The reflected light is measured with a spectrometer and then converted to refractive index units (RIU). The presented sensor measures the refractive index in the range of 1.30–1.38 RIU with an accuracy of 2×10−4 RIU.
