Formation of Fiber Tapers by Chemical Etching for Application in Fiber Sensors and Lasers

A method of safe chemical etching of optical fibers for their subsequent application in sensor and laser technologies has been developed. A series of thinned fibers (tapers) with diameters of the thin part of 5.7 to 24.1 mu m and lengths of 2.3 to 11.1 mm was prepared. Using a frequency reflectometer, the location of the resulting losses in small-diameter tapers is shown. There is a strong dependence of the losses that occur on defects on the surfaces of cones and the cylindrical part of a taper. LMR resonances were observed in the transmission spectra of large-diameter tapers when thin ZnTe films were deposited on them. Their sensitivity to changes in the refractive index of aqueous solutions was 5230 nm/RIU (refractive index unit). A polymer composite with Bi2Se3, MoSe2, and NiO nanopowders was applied to tapers with diameters of less than 10 mu m. They were used in this form as passive Q-factor switches in a ring fiber erbium laser.