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    Strain sensitivity enhancement in suspended core fiber tapers
    (Heidelberg : Springer, 2013) André, R.M.; Silva, S.O.; Becker, M.; Schuster, K.; Rothardt, M.; Bartelt, H.; Marques, M.B.; Frazão, O.
    Suspended core fiber tapers with different cross sections (with diameters from 70 μm to 120 μm) are produced by filament heating. Before obtaining the taper, the spectral behavior of the suspended core fiber is a multimode interference structure. When the taper is made, an intermodal interference between a few modes is observed. This effect is clearly visible for low taper core dimensions. Since the core and cladding do not collapse, two taper regions exist, one in the core and the other in the cladding. The cladding taper does not affect the light transmission, only the core is reduced to a microtaper. The spectral response of the microtaper based-suspended core fiber is similar to a beat of two interferometers. The strain is applied to the microtaper, and with the reduction in the transverse area, an increase in sensitivity is observed. When the taper is immersed in a liquid with a different index of refraction or subjected to temperature variations, no spectral change occurs.
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    Volume fraction determination of binary liquid mixtures by measurement of the equalization wavelength
    (Basel : MDPI, 2010) Martincek, I.; Pudis, D.; Kacik, D.; Schuster, K.
    A method for determination of the volume fraction in binary liquid mixtures by measurement of the equalization wavelength of intermodal interference of modes LP01 and LP11 in a liquid core optical fiber is presented in this paper. This method was studied using a liquid core optical fiber with fused silica cladding and a core made up of a binary silicon oil/chloroform liquid mixture with different volume fractions of chloroform. The interference technique used allows us to determine the chloroform volume fraction in the binary mixture with accuracy better than 0.1%. One of the most attractive advantages of presented method is very small volume of investigated mixture needed, as only a few hundred picoliters are necessary for reliable results. © 2010 by the authors.