BENT OPTICAL FIBER TAPER FOR REFRACTIVE INDEX MEASUREMENTS WITH TUNABLE SENSITIVITY

Abstract

This letter presents experimental results of a refractive index sensor using a bent optical fiber taper. The approach of this sensor is based on an in-line Michelson interferometer implemented with a single mode tapered fiber with a cleaved tip end and changing tilt angle, enabling to tune its refractive index sensitivity. Several radii of curvature are tested and their refractive index sensitivities are analyzed for a refractive index range between 1.333 and 1.405. A clear enhancement of the sensor response is achieved at specific taper bending radii. A substantial improvement in the refractive index sensitivity, at values very close to distilled water, is obtained with a radius of curvature of 11 mm. A significant enhancement of the sensor response is also achieved for a refractive index close to 1.40 with a radius of curvature of 16.5 mm. (c) 2015 Wiley Periodicals, Inc. Microwave Opt Technol Lett 57:921-924, 2015