Browsing by Author "D, Niveditha"

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    TIGHT FOCUSING OF AZIMUTHALLY POLARIZED AXISYMMETRIC BESSEL-MODULATED GAUSSIAN VORTEX
    (Coimbatore Institute of Technology, Coimbatore jointly with Bergen University college , Norway, 2015-12-02) D, Niveditha
    Focusing properties of the azimuthally polarized axisymmetric Bessel-modulated Gaussian beam optical vortex focused through a dielectric interface by in high numerical aperture system is investigated theoretically by vector diffraction theory. Results show that intensity distribution in focal region can be altered considerably by beam parameter μ and polarization angle. While μ alters axial intensity distribution remarkably, focal splitting may occur with tunable focal shift, and real value μ also may induce local intensity minimum. For certain case, with increasing imaginary value μ, transverse focal spot shrinks accompanied with higher full width half maximum of axial intensity distribution,which is suitable for application such as optical manipulation and optical trapping.
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    TIGHT FOCUSING OF AZIMUTHALLY POLARIZED COSH GAUSSIAN VORTEX BEAMS THROUGH DIELECTRIC INTERFACE
    (PSGR Krishnammal College for Women, 2015-12-07) D, Niveditha
    Focusing properties of the azimuthally polarized Cosh Gaussian beam optical vortex focused through a dielectric interface by in high numerical aperture system is investigated theoretically by vector diffraction theory. Results show that intensity distribution in focal region can be altered considerably by beam ratio β and beam order. Increase in beam order and beam ratio, the spot size is found to be reduced and improvement in the focal depth is observed. The side lobe intensity is found to increase with increase in beam order for every beam ratio considered. Thus by properly increasing the beam ratio value and beam order generates a highly confined focal spot with maximum side lobe intensity maximum depth of focus. This beam finds application in Optical trapping , high resolution imaging and Optical recording