ABSTRACT
The presented research shows the possibilities of creating in-line magnetic sensors based on the detection of changes of light propagation parameters, especially polarization, obtained by mixing Fe3O4 nanoparticles with hexadecane (higher alkane) surrounding a biconical optical fiber taper. The fiber optic taper allows to directly influence light parameters inside the taper without the necessity to lead the beam out of the structure. The mixture of hexadecane and Fe3O4 nanoparticles forms a special cladding surrounding a fiber taper which can be controlled by external factors such as the magnetic field. Described studies show changes of transmission (power, loss) and polarization properties like azimuth, and ellipticity, depending on the location of the mixture on sections of tapered optical fiber. The taper was made of a standard single-mode telecommunication fiber, stretched out to a length of 20.0 ± 0.5 mm and the diameter of the tapers is around 15.0 ± 0.3 µm, with the loss lower than 0.5 dB @ 1550 nm. Such a taper causes the beam to leak out of the waist structure and allows the addition of the external beam-controlling cladding material. The presented research can be used to build polarization switches or optical sensor. The results show that it can be a new way to control the propagation parameters of a light beam using tapered optical fiber and magnetic mixture.
ABSTRACT
The paper investigates the effect of thermo-optic switching resulting from the hybrid combination of a tapered optical fiber (TOF) with alkanes doped with nanoparticles of zinc sulfide doped with manganese (ZnS:Mn NP). Presented measurements focused on controlling losses in an optical fiber by modification of a TOF cladding by the alkanes used, characterized by phase change. Temperature changes cause power transmission changes creating a switcher or a sensor working in an ON-OFF mode. Phase change temperatures and changes in the refractive index of the alkane used directly affected power switching. Alkanes were doped with ZnS:Mn NPs to change the hysteresis observed between ON-OFF modes in pure alkanes. The addition of nanoparticles (NPs) reduces the difference between phase changes due to improved thermal conductivity and introduces extra nucleating agents. Results are presented in the wide optical range of 550-1200 nm. In this investigation, hexadecane and heptadecane were a new cladding for TOF. The higher alkanes were doped with ZnS: Mn NPs in an alkane volume of 1 wt.% and 5 wt.%. The thermo-optic effect can be applied to manufacture a thermo-optic switcher or a temperature threshold sensor.
