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-The paper presents comparison of thermal and optical properties of the typical commercial available and manufactured in our laboratory poly(methyl metacrylate) polymer useful in polymer optical fibers technology. The thermal studies were made by thermogravimeter connected on-line with FT-IR and QMS spectrometer, the optical properties were characterized by spectral attenuation measurements. It was found that polymer obtained in our laboratory is characterized by higher temperature (about 100 0 C) of beginning mass loss occurred and lower attenuation then commercial available polymer.Microstructured optical fibers (MOFs) provide extra degrees of freedom in manipulating the optical properties of light, such as dispersion, nonlinearity, and birefringence [1][2][3][4][5]. Therefore they have attracted increased interest over the last two decades. Due to specific material properties, the technology of microstructured polymer optical fibers (mPOF) has been intensively developed in recent years. Polymer fibers may show better parameters than fibers made of silica glass in a variety of applications. One of the advantages is biological compatibility, which opens the possibility for medical applications. Moreover polymers have higher flexibility than silica glass, therefore can withstand much higher strains, which enables applications of polymer fibers as elongation sensors in a strain range unattainable for silica fibers [6]. In order to obtain a polymer optical fiber with the proper optical characteristics, it is necessary to prepare specific preform from which optical fibers are drawn or extruded. Now polymer optical fibers are mainly manufactured from poly(methyl methacrylate) PMMA (linear polymer), produced by the polymerization of methyl methacrylate. Unfortunately the main disadvantage of "PMMA optical fibers" is their very high losses, in comparison with "silica fibers", mainly caused by C-H bonds and impurities. In this letter we present the low loss poly(methyl metacrylate) polymer manufactured in our Laboratory. The manufactured from our polymer mPOF was characterized by significant decrease of the losses.* E-mail: pawel.mergo@poczta.umcs.lublin.pl A sample of "our PMMA" was prepared from methyl methacrylate (ALDRICH). In polymer technology two methods of polymerization are used -thermal and photopolimerization. The chemical reaction, essentially, takes place in the same way, except the source of initiation. Due to the crosslinking of the polymer during photopolymerization, this technique is not used in the polymer optical fibers technology. A very important issue in the production of materials for optical applications is their purity. Even a small amount of impurities can significantly decrease the transmission properties of the final product such as an optical fiber. Therefore, MMA was purified before starting the process of polymerization. The purification is performed by distillation process in under pressure conditions getting rid of impurities as well as undesirable inhibitor, which is added to ...

We report on experimental studies of polarimetric sensitivity to torsion in spun highly birefringent fibers. Two classes of spun fibers were examined, namely spun side-hole fibers and birefringent microstructured fibers with different birefringence dispersion, spin pitches, and spin directions. The polarimetric sensitivity to torsion was determined by monitoring a displacement of the spectral interference fringes arising in the output signal because of interference of polarization modes and induced by an additional fiber twist. Both the experimental results and the analytical predictions showed that the sensitivity to torsion normalized to the fringe width in the spun highly birefringent fibers increased asymptotically with the twist rate to the value of 1/ π rad−1. We have also studied the polarimetric response to temperature in the spun side-hole fibers. We have found that, in contrast to the torsional sensitivity, the temperature sensitivity decays asymptotically to zero with increasing fiber twist rate. Therefore, the spun fibers with short spin pitches are especially well suited for torsion measurements because the torsional sensitivity and the range of linear response are both enhanced in such fibers, while at the same time, the cross-sensitivity to temperature is reduced.

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Liquid crystal circular core optical fibers cannot have a stable structure of arrangement because of misfit of core geometry and properties of liquid crystals. Fibers of high ellipticity of core are much better in this case but controlling the state and degree of arrangement of a liquid crystal by external electric field requires application of high voltage. The work presents the technology of substrate of liquid crystal core fibers in the form of quartz glass capillaries with highly elliptic central hole and two additional holes placed at both sides of the central one along the fiber. On the surface of side holes layers of nickel were deposited by thermal decomposition of nickel carbonyl from a gaseous phase.Substrates 2m long with dimensions of central hole 4xl8jtm were obtained and characterized. The produced substrates may allow preparation of a new generation of liquid crystal core fibers. The work also presents the design of laboratory scale apparatus for preparation of nickel carbonyl as well as conditions of its synthesis.