Browsing by Author "Thiruarul D"

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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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    ENGINEERING AXIALLY POLARIZED SUB-WAVELENGTH SCALE FOCAL STRUCTURES USING ANNULAR WALSH FILTER
    (Springer Link, 2023) Umamageswari N; Thiruarul D; Lavanya M; William Charles J; Jaroszewicz; Rajesh K B
    Based on vector diffraction theory, the tight focusing properties of radially polarized Bessel Gaussian beam (BGB), phase modulated by annular Walsh function filters and focused by a high NA parabolic mirror system are studied numerically. The annular Walsh filter derived from the annular Walsh functions forms a complete set of orthogonal phase filters that takes values of either 0 or π phase corresponding to + 1 or −1 over the domain specified by the inner and outer radii of the annulus. Numerical results show that by properly modulating the annular obstruction of Walsh filter and pupil to beam ratio of the input BGB, one can generate many novel focal patterns such as three-dimensional multiple sub-wavelength scale focal spot segments, optical needle, axial flat top profile, etc. We expect that such three-dimensional chain of focal structures is useful for nano-lithography, particle trapping and transportation, as well as confocal and STED microscopy, microstructure fabrication and so on.
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    ENGINEERING AXIALLY POLARIZED SUB-WAVELENGTH SCALE FOCAL STRUCTURES USING ANNULAR WALSH FILTER
    (SpringerLink, 2023) Umamageswari N; Thiruarul D; Lavanya M; William Charles J; Jaroszewicz; Rajesh K.B
    Based on vector diffraction theory, the tight focusing properties of radially polarized Bessel Gaussian beam (BGB), phase modulated by annular Walsh function filters and focused by a high NA parabolic mirror system are studied numerically. The annular Walsh filter derived from the annular Walsh functions forms a complete set of orthogonal phase filters that takes values of either 0 or π phase corresponding to + 1 or −1 over the domain specified by the inner and outer radii of the annulus. Numerical results show that by properly modulating the annular obstruction of Walsh filter and pupil to beam ratio of the input BGB, one can generate many novel focal patterns such as three-dimensional multiple sub-wavelength scale focal spot segments, optical needle, axial flat top profile, etc. We expect that such three-dimensional chain of focal structures is useful for nano-lithography, particle trapping and transportation, as well as confocal and STED microscopy, microstructure fabrication and so on.
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    GENERATION OF AXIAL MULTI FOCI PATTERN
    (Research Square, 2022-10-14) Thiruarul D; William Charles J; Lavanya M; Rajesh K.B; Jaroszewicz Z
    Axially splitted multi foci(AMF) are numerically generated by tight focusing of higher order cylindrical vector beam(HCVB) through an annular Walsh filter .Here we report that by properly manipulating the parameters of HCVB such as initial phase(φ0 ),topological charge (m), polarization rotation angle or azimuthal index (a) and suitably phase modulated with a Walsh function filter of fixed orders (n) and annular obstruction (ε),onecan generate axially polarized multiple spots,transversely polarized multiple holes,transversely polarized multi spots,axially and transversely polarized multi holes with extended central annular region.These distributions may be useful for multiple optical trapping and axial superresolution microscopy.
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    GENERATION OF AXIALLY SPLITTED ULTRA-LONG MULTIPLE OPTICAL NEEDLES/OPTICAL TUBES USING GENERALIZED CYLINDRICAL VECTOR BESSEL GAUSSIAN BEAM PHASE MODULATED BY ANNULAR WALSH FUNCTION FILTER
    (Springer Link, 2022-08-29) Thiruarul D; William Charles J; Lavanya M; Rajesh K B; Jaroszewicz Z
    Based on vector diffraction theory and annular Walsh function filter, axially splitted ultra-long multiple optical needles/optical tubes of electric as well as magnetic field distributions are numerically generated by generalized cylindrical vector Bessel Gaussian beam phase modulated by annular Walsh function filter. This multiple optical structures can be conveniently tailored by properly tuning the initial phase of the Cylindrical vector beam (CVB) and Walsh order of the annular Walsh function filter. Furthermore, the effect of energy flux density (Poynting vector) as well as Spin angular momentum(SAM) distribution in the focal region are theoretically analyzed. We expect that such an axially splitted focal systems could be applicable in optical trapping and manipulation of multiple particles, optical super resolution microscopy etc.
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    GENERATION OF AXIALLY SPLITTED ULTRA-LONG MULTIPLE OPTICAL NEEDLES/OPTICAL TUBES USING GENERALIZED CYLINDRICAL VECTOR BESSEL GAUSSIAN BEAM PHASE MODULATED BY ANNULAR WALSH FUNCTION FILTER
    (SpringerLink, 2022-08-29) Thiruarul D; William Charles J; Lavanya M; Rajesh K.B; Jaroszewicz Z
    Based on vector diffraction theory and annular Walsh function filter, axially splitted ultra-long multiple optical needles/optical tubes of electric as well as magnetic field distributions are numerically generated by generalized cylindrical vector Bessel Gaussian beam phase modulated by annular Walsh function filter. This multiple optical structures can be conveniently tailored by properly tuning the initial phase of the Cylindrical vector beam (CVB) and Walsh order of the annular Walsh function filter. Furthermore, the effect of energy flux density (Poynting vector) as well as Spin angular momentum(SAM) distribution in the focal region are theoretically analyzed. We expect that such an axially splitted focal systems could be applicable in optical trapping and manipulation of multiple particles, optical super resolution microscopy etc.
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    GENERATION OF MULTIPLE FOCAL PATTERN VIA PHASE MODULATED RADIAL AND AZIMUTHAL VARIANT VECTOR BEAM
    (Springer, 2023-03-07) Thiruarul D; William Charles J; Lavanya M; Rajesh K.B; Jaroszewicz Z
    The multiple focal patterns such as longitudinally/transversely polarized multiple focal spots/holes, longitudinally/transversely polarized annular dark multiple spots with petal shapes are in high demand for applications such as multiple optical trapping and manipulating, light-sheet fluorescence microscopy and optical lithography. This article numerically demonstrated the possibility of achieving the above task by subjecting phase modulation of radial and azimuthal variant vector beam through suitable annular Walsh function filter. Here it is demonstrated that the inherited self similarity properties of annular Walsh function and the flexibility of tuning the radial and azimuthal index of input beam is a state of art in landscaping multiple focal segment of desirable spatial and polarization distribution.
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    GENERATION OF SUB-WAVELENGTH LONGITUDINAL MAGNETIZATION NEEDLE AND MULTIPLE LONGITUDINAL SPOTS USING CIRCULARLY POLARIZED BEAM THROUGH AN ANNULAR WALSH FUNCTION FILTER
    (Springer Link, 2023-11-17) Thiruarul D; William Charles J; Lavanya M; Rajesh K B; Jaroszewicz Z
    This numerical work demonstrates the possibility of generating sub wavelength scale magnetization spot of long focal depth and axially separated multiple magnetization segments using annular Walsh function filter. Numerical result calculated on the basis of vector diffraction theory (VDT) and Inverse Faraday Effect (IFE) shows upon suitably choosing the parameters of Walsh function filter such as order and annular obstruction, one can generate and tune the longitudinal magnetization needle and multiple magnetization spots in the focal plane for the input circularly polarized Bessel Gaussian beam. The generated sub wavelength magnetization structures are highly applicable in fields such as all-optical magnetic recording, multiple trapping and transportation of magnetic particles, magnetic resonance microscopy and multilayer ultra-high-density magnetic storage.
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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.