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Optical fibers can support various modal forms, including vector modes, linear polarization (LP) modes, and orbital angular momentum (OAM) modes, etc. The modal correlation among these modes is investigated via Jones matrix, associated with polarization and helical phase corresponding to spin angular momentum (SAM) and OAM of light, respectively. We can generate different modal forms by adopting superposed helical gratings (SHGs) with opposite helix orientations. Detailed analysis and discussion on mode conversion is given as for mode coupling in optical fibers with both low and high contrast index, respectively. Our study may deepen the understanding for various fiber guided modes and mode conversion among them via fiber gratings

The influence of heat treatment and substrate materials on PLT thin films by sol-gel processing has been researched. Epitaxial growth PLT thin films with perovskite-type structure on sapphire, SrTiO3 and MgO single crystal substrates have been prepared. The epitaxial relations are (100)PLT28/(100)SrTiO3, (111)PLT28//(0001)sapphire and (100)PLT14//(100)MgO. The PLT polycrystal thin films with perovskite-type structure on Si single crystal and quartz glass substrates have been prepared. The remanent polarization Pr and the coercive field Ec of PLT15 ceramic thin films are 7.7 μc/cm2 and 34 kv/cm at 4 KHz respectively. The optical transmittance of PLT28 ceramic thin films within the wavelength range of λ = 500–1000 nm is approximately 80%.

PbTiO 3 polycrystalline thin films with perovskite structure have been prepared on an Si single-crystal substrate by sol-gel processing. Highly oriented perovskite PbTiO 3 thin films have also been prepared on MgO and SrTiO 3 single-crystal substrates. The PbTiO 3 thin films have good ferroelectricity and pyroelectricity. The values of spontaneous polarization P s , remanent polarization P r and coercive field E c of the PbTiO 3 polycrystalline thin films are 30 μC/cm 2 , 15 μC/cm 2 and 50 kV/cm, respectively. The polycrystalline thin films have a high pyroelectric coefficient γ of 2.9 × 10 −8 C/cm 2 K, high figure of merit for voltage responsivity F v (=γ/ C v e r ) of 60 × 10 −12 C cm/J and a figure of merit for specific detectivity F m (=γ/ C v (e r tg δ) 1/2 ) of 0.74 × 10 −8 C cm/J.

Barium titanate gels were prepared from barium acetate and tetrabutyl titanate by sol-gel processing. The results of DTA and XRD showed that as-prepared gels were transformed into crystalline with tetragonal ferroelectric phase by a heat treatment at 600°C. It was found that soaking the BaTiO3 crystalline powders in nitric acid could increase the density of the ceramic bodies. The density of the resultant bodies is near 96% of the theoretical value. The dielectric measurement on most of the ceramic bodies showed that the magnitude of dielectric constant is 16,000 at its peak and 2500 at room temperature. D-E hysteresis loop was observed.

Ni64B36 glass has been investigated by X-ray diffraction, and conventional and pulse neutron diffraction, and evidence of first neighbour boron-boron atoms has been obtained.

The effects of cold-rolling on the atomic structure of a Fe40Ni40P14B6 commercial metallic glass (Metglas 2826) have been investigated by X-ray and neutron diffraction. The cold-rolling is seen to produce significant changes in the structure factorS(Q) of this glass, and the changes observed are the reverse of those caused by low temperature annealing. The structure factor of the rolled specimen has also been simulated numerically. This shows that the changes in structure factor observed are consistent with a heterogeneous deformation, in which approximately 10% of the sample volume appears to have an atomic arrangement which is less well ordered than in the as-received glass. The deformation produced by rolling has finally been removed by a heat treatment whose parameters were determined with reference to a current model of structural relaxation.

Hydrogen is used as a probe for obtaining structural information on TiCu metallic glasses. Resulte from experimental radial distribution functions of hydrided and un- hydrided TiCu glasses show a significant change in the nearest neighbor distance between Ti and Cu atom. The measured distance suggests that hydrogen occupies mainly tetrahedral sites defined by Ti and Cu atoms under following hydriding conditions (85 atm H2–80°C).