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13 results on '"Wu, Guoan"'

1. Comb mode converters based on sampled helical gratings

Author

Ma, Yancheng, Fang, Liang, and Wu, Guoan

Subjects
Physics - Optics
Abstract

Helical gratings (HGs) have an achievement of flexible mode conversion for fibre guided orbital angular momentum (OAM) modes. Sampled reflection HGs can realise the generation and conversion of OAM mode with comb spectra. They can be used to simultaneously filter wavelengths and convert modes, and thus may be applied to the hybrid multiplexing technology with wavelength division multiplexing and mode division multiplexing.

Published
2019

2. Fiber guided mode analyses and conversion using superposed helical gratings

Author

Ma, Yancheng, Fang, Liang, and Wu, Guoan

Subjects
Physics - Optics
Abstract

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

Published
2019
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13. An investigation of the influence of cold-rolling on the structure factor of a metallic glass

Author

Wu Guoan, Neil Cowlam, and M.R.J. Gibbs

Subjects
Amorphous metal, Materials science, Mechanical Engineering, Neutron diffraction, Annealing (glass), Sample volume, Crystallography, Mechanics of Materials, Solid mechanics, X-ray crystallography, Metglas, General Materials Science, Composite material, Structure factor
Abstract

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.

Published
1984

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