Sensor de absorção por campo evanescente com fibra óptica

Abstract

In this work optical fibers anci nanometrical wavelenghts are useci to perform chemical measurements. The optical fiber is part of the optical sensor, not only as a waveguicie. This sensor emerges as a more sensible, precise anci faster option when compareci to conventional measurement anci analysis methocis. A ciye concentration sensor that uses the technique of the evanescent fielci absorption of an optical fiber is analiseci, built anci essayeci. The fiber portion, which constitutes the sensur, is a smooth transition taper, generateci by the fiber stretching by heat. This sensor operates at 633 nm for the crystal violet ciye with a singlemocie optical fiber. The theory useci to calculate the power attenuation of the sensor fiber guicieci light is presenteci. A theoretical performance confrontation of the sensor using singlemocie, multimocie, iluminateci by ciifferent light sources anci ciifl'erent taper ciimensions is realized. The sensor fabrication methoci is ciescribeci as well as the light power measurement process for some dye concentrations. The experimental results for attenuation vs. ciye concentration are presented anci compareci to the theoretical values. The essays, which refer to each one of the built tapers, have been realizeci using 5 ciifferent ciye concentrations anci, at least, 4 repetitions for each one.