This study presents the doping of higher alkanes, namely, pentadecane (C15) and hexadecane (C16), with ZnS:Mn nanoparticles to create new types of in-line optical fiber sensors with unique optical properties. In this research, the phenomenon of light beam leakage out of the taper and its interaction with the surrounding materials is described. The fabricated new materials are used as cladding in a tapered optical fiber to make it possible to control the optical light beam. The manufactured sensor shows high sensitivity and fast response to the change in the applied materials. Results are presented for a wide optical range of 1200-1700 nm with the use of a supercontinuum source and an optical spectrum analyzer, as well as for a single wavelength of 800 nm, corresponding to the highest transmitted power. The results present a change in the optical property dependence on the temperature in the cooling and heating process. For all materials, the measurements in a climatic chamber are provided between 0 and 40 °C, corresponding to the phase change of the alkanes from solid to liquid. The addition of nanoparticles to the volume of alkanes is equal to 1 wt%. To avoid a conglomeration of nanoparticles, the anti-agglomeration material, Brij 78 P, is used.
Keywords: advancements in fiber forming technologies; fiber technology; functional micro- and nanofibers for miniaturisation technologies; higher alkanes; nanoparticles; optical fiber taper; sensors.