Miniature fiber-optic high temperature sensor based on a hybrid structured Fabry-Perot interferometer

A miniature Fabry-Perot (FP) interferometric fiber-optic sensor suitable for high-temperature sensing is proposed and demonstrated. The sensor head consists of two FP cavities formed by fusion splicing a short hollow-core fiber and a piece of single-mode fiber at a photonic crystal fiber in series. The reflection spectra of an implemented sensor are measured at several temperatures and analyzed in the spatial frequency domain. The experiment shows that the thermal-optic effect of the cavity material is much more appreciable than its thermal expansion. The temperature measurements up to 1000 degrees C with a step of 50 degrees C confirm that it could be applicable as a high-temperature sensor.     

Removal of rare earth elements from a U/RE ingot via a reaction with UCl3

Journal of Radioanalytical and Nuclear Chemistry - A chemical equilibrium experiment was conducted to remove rare earth (RE) elements from a U/RE ingot using UCl3 as an oxidant. Upon analysis, the...     

Uranium recovery via melt separation of rare earth elements and chemical oxidation

Journal of Radioanalytical and Nuclear Chemistry - Pyroprocessing of spent fuels, especially the recovery of U, improves the overall efficiency of nuclear recycling. The recovery of U/Transuranic...     

Molecular engineering. 8. Kinetic and conformational studies of resorcin [4]arene-based C4 tetraoxatetrathiahemicarceplexes: carceroisomerism and twistomerism

New C(4v) tetraoxatetrathiahemicarcerands and their six hemicarceplexes containing DMF, DMA, DMSO, or NMP were synthesized and characterized. Their conformations, kinetic properties, carceroisomerism, and twistomerism were studied by VT, 2D COSY, NOESY, and ROESY (1)H NMR experiments. The decomplexation rates of DMF or DMA were very slow with high activation energy barriers (73 and 104 kJ mol(-1), respectively) and the complexed guests feel more constriction than their free liquid state. The largest isomerization energy barrier of carceroisomers was 15.4 kcal mol(-1), and the isomerization energy barriers of twistomers are significantly larger than those of carceroisomers.     

Die isosterische Adsorptionsw?rme an heterogenen Oberfl?chen

Ohne Zusammenfassung     

Small cavitands specifically binding a water molecule

[structure: see text] Three new C(2v) cavitands based on resorcin[4]arene bind water specifically at low temperature in CD(2)Cl(2) or CDCl(3) due to their complementarity to water as well as the solvophobic interaction. The averaged DeltaH(o) and DeltaS(o) values are -2.3 kcal mol(-1) and -128 cal mol(-1) K(-1), which gave the averaged -DeltaG(o) of 1.9 kcal mol(-1) at -50 degrees C in water saturated CD(2)Cl(2).     

Fabrication of helical long-period fiber gratings by use of a CO2 laser

We present a method of helical long-period fiber grating (H-LPFG) fabrication by use of a CO2 laser for use as an optical torque sensor. A conventional optical fiber grating has periodic vertical index changes along its fiber axis, but a H-LPFG has a screw-type index modulation. The helical index modulation is obtained with the asymmetric index change caused by a single-side laser beam exposure. The H-LPFG shows peak shifts with codirectional or contradirectional torsion to the helix. Also, the polarization-dependent loss is measured to be relatively small compared with that of a conventional long-period fiber grating.     

Determination of stress-induced intrinsic birefringence in a single-mode fiber by measurement of the two-dimensional stress profile

The two-dimensional (2-D) axial stress profile of a single-mode fiber is obtained with an optical tomographic measurement technique. All stress components of the fiber are calculated from a measured axial stress profile. We demonstrate that the differential group delay induced by intrinsic nonsymmetric stress as well as the induced linear birefringence between two orthogonal polarization modes can be determined with an analytic technique based on a vector perturbation method from a measured asymmetric 2-D stress distribution.     

Measurement of refractive-index variation with temperature by use of long-period fiber gratings

The thermo-optic coefficient of the core material of a fiber is analyzed by use of a pair of long-period fiber gratings. First the effective index difference between the core and the cladding modes is measured from the peaks of the interference fringe generated by the grating pair. The order of the cladding mode is decided by the cutoff wavelength and the numerical aperture of the fiber. The material index of the fiber core is obtained in terms of wavelength. At each wavelength the index is chosen to minimize the difference between the measured and the calculated spectra of the grating pair. Finally the thermo-optic coefficient of the fiber core is calculated by repetition of the measurement at different temperatures. With a germanosilicate-core fiber and a boron codoped germanosilicate-core fiber, the thermo-optic coefficients were 1.1x10(-5)/( degrees )C and 0.75x10(-5)/( degrees )C, respectively.     

Spectral polarization-dependent loss of cascaded long-period fiber gratings

We have measured the spectral polarization-dependent losses of cascaded long-period fiber gratings composed of single, double, and triple identical gratings and fabricated by exposure of a UV laser beam on one side of a fiber. The measurement was made by use of the Mueller matrix method for scanning the wavelength of the incident beam. The polarization-dependent loss was dramatically increased as the number of cascaded gratings was increased. The formation of the UV-induced geometric birefringence in the fiber grating and its relationship to the fine interference fringes formed by cascading gratings are discussed.