Sensor applications of photosensitive capillary waveguides

Abstract

We describe a photosensitive capillary waveguide sensor, composed of a capillary structure with a photosensitive cladding ring surrounding the bore. The bore is filled with a fluid having an index of refraction that is sensitive to a measurand of interest, and a grating is inscribed in the cladding ring. We measure the optical interaction between light propagating in the filled capillary waveguide and the grating to determine the parameter of interest. Methods for forming connections between the capillary and single mode optical fiber are also described. We demonstrate the performance of the capillary waveguide as a temperature sensor in which the sensitivity of the Bragg wavelength to temperature is -150 pm/°C. We also describe how to use the capillary waveguide sensor to discriminate between different measurands.