Browsing by Author "Mahadevan G"

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    ENERGY FLUX DENSITY FOR HIGHER-ORDER CYLINDRICAL VECTOR VORTEX BEAM TIGHTLY FOCUSED THROUGH A DIELECTRIC INTERFACE
    (Springer India, 2021) Lavanya M; Thiruarul D; Rajesh KB; Mahadevan G; Dhayalan, Velauthapillai; Jaroszewicz Z
    Energy flux density for higher-order cylindrical vector vortex (HCVV) beam focused through a dielectric interface is analyzed numerically based on vector diffraction theory. Numerical results shows variation in the direction of the energy flux or Poynting vector distribution both in transverse and longitudinal plane upon suitably tuning the topological charge and polarization order of HCVV beam. We also note that the strong reverse flow of energy occur at the centre of the focal plane for certain values of the topological charge and polarization order. These results may find potential applications in optical trapping and optical manipulations.
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    GENERATION OF 1D ARRAY OF FOCAL SEGMENTS USING SPIRALLY POLARIZED BEAM AND COMPLEX PHASE FILTER
    (Elsevier, 2022-05) Senthilkumar M; Udhayakumar M; Lavanya M; Mahadevan G; Rajesh K.B; Jaroszewicz Z
    A new approach for generating and tuning 1D array of sub wavelength scale electric and magnetic spot, hole, flattop and bubble profiled segments using tightly focused spirally polarized beam phase and amplitude modulated with suitable complex phase filter is proposed and investigated numerically using vector diffraction theory. Numerical result shows that by using a well optimized single Complex Phase Filter (CPF), one can generated and tune the geometry of the 1D chain of electric and magnetic field distribution from sub wavelength scale hole to spot and then to a chain of flattop profiled or bubble structure segments by properly tuning the spirallity of incident spirally polarized beam. These focal field distributions may find potential applications in laser direct writing and optical microscopy, as well as multiple-particle trapping, alignment, and acceleration along the optical axis.
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    GENERATION OF 1D ARRAY OF FOCAL SEGMENTS USING SPIRALLY POLARIZED BEAM AND COMPLEX PHASE FILTER
    (Elsevier, 2022-05) Senthilkumar M; Udhayakumar M; Lavanya M; Mahadevan G; Rajesh K B; Jaroszewicz Z
    A new approach for generating and tuning 1D array of sub wavelength scale electric and magnetic spot, hole, flattop and bubble profiled segments using tightly focused spirally polarized beam phase and amplitude modulated with suitable complex phase filter is proposed and investigated numerically using vector diffraction theory. Numerical result shows that by using a well optimized single Complex Phase Filter (CPF), one can generated and tune the geometry of the 1D chain of electric and magnetic field distribution from sub wavelength scale hole to spot and then to a chain of flattop profiled or bubble structure segments by properly tuning the spirallity of incident spirally polarized beam. These focal field distributions may find potential applications in laser direct writing and optical microscopy, as well as multiple-particle trapping, alignment, and acceleration along the optical axis.
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    GENERATION OF ULTRA-LONG MULTIPLE OPTICAL TUBES USING ANNULAR WALSH FUNCTION FILTERS
    (Springer, 2020-08-29) Thiruarul D; Rajesh K B; Lavanya M; Mahadevan G; Dhayalan, Velauthapillai; Jaroszewicz Z
    The tight focusing properties of an azimuthally polarized Bessel Gaussian beam phase modulated by annular Walsh function filter is studied numerically by vector diffraction theory. It is observed that upon suitable optimization of order and annular obstruction ratio of an annular Walsh function filter, one can generate multiple sub wavelength scale optical tubes (optical holes) with super long focal depth. Such a focal system is usable for Nano-lithography, particle trapping and transportation, as well as confocal and STED microscopy, microstructure fabrication etc.
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    TIGHT FOCUSING PROPERTIES OF CIRCULARLY POLARIZED ANNULAR MULTI-GAUSSIAN BEAM THROUGH A UNIAXIAL BIREFRINGENT CRYSTAL
    (International Journal of Optics and Photonic Engineering,Vibgyor Publishers.org, 2010-10-24) Murugesan R; ThiruArul D; Rajesh K B; Lavanya M; Mahadevan G
    Focusing properties of circularly polarized annular multi-Gaussian beams through a uniaxial birefringent crystal is investigated numerically by vectorial Debye theory. Results show that the optical intensity in focal region of circularly polarized annular multi-Gaussian beams can be altered considerably by the topological charge [n], beam order [m] and birefringence [Δn]. Many novel focal structures such as focal spot, focal hole and flat top profile of sub wavelength structure are achieved.