Authors: R Chandrasekaran K Prabakaran K B Rajesh
Publish Date: 2015/12/19
Volume: 48, Issue: 1, Pages: 39-
Abstract
We investigated the focusing properties of a cylindrically polarized annular multi Gaussian beam tightly focused with a high NA lens and a complex phase filter It is observed that a properly designed complex phase filter can generate multiple focal spot and focal hole segments along optical axis its useful for the manipulation of multiple optical traps of low and high refractive index particlesRecently there is an increasing interest in the spatially inhomogeneous polarization mostly driven by the advances made in microfabrication techniques and theoretical modeling techniques that were not available homogeneous polarization One example of such spatially inhomogeneous polarization that has attracted much of the interest is the socalled cylindrical vector CV beams Cylindrical vector beams are solutions of Maxwell equations that obey cylindrical symmetry both in amplitude and polarization Cylindrical vector beams can be divided into radially polarization azimuthal polarization and generalized cylindrical polarization according to the actual polarization pattern One can use two cascaded halfwave plates to conveniently convert a radially polarization or azimuthal polarization into a generalized cylindrical vector beam or vice versa Zhan and Leger 2002 Friedman et al 2002 Growing interest in the generation of threedimensional 3D optical beams that are dark regions in space surrounded by light are driven by wide ranging applications including dark optical traps for atoms Zhan and Leger 2002 Friedman et al 2002 manipulation guiding and binding of microparticles and biological cells Cizmar et al 2010 erase beams for superresolution fluorescence microscopy Watanabe et al 2003 etc Over the past years a variety of techniques have been proposed for generating such optical bottle beams for applications in optical tweezers and atom traps GarciaSucerquia et al 2004 Chen and Zhan 2006 Bokor and Davidson 2006 Ahluwalia et al 2006 Arlt and Padgett 2000 Ahluwalia et al 2004 Yelin et al 2004 Pu et al 2005 However stable trapping of a single particle is expected if we can make the bottles small enough and comparable to the particle size Such “microbottles” were established recently with the volume speckle field Isenhower et al 2009 Recently particle trapping experiment is successfully done by Ashkin et al 1986 particles manipulations have drawn great interests For example owning to the abilities to manipulate and isolate microscopic objects in a precise and nondestructive manner optical tweezers are widely used in micromachines and microscopy Unger and Marston 1988 Crocker and Grier 1994 Wright et al 1990 Tadir et al 1989 In order to improve the speed of particle trapping the optical tweezers with multitraps are ideal Huang et al 2011 Guo et al 2011 In 2002 two dimensional arrays of focal spots are formed by multi beam systems Eriksen et al 2002 However it is just for two dimensional particles trapping In 2005 Casaburi et al 2005 achieve multi3Doptical trapping by utilizing two and threebeam interference which in order to ensure destructive interference at the focus require extremely high interferometric precision among the three beams Recently several methods to generate the multiple optical trapping have been suggested Prabakaran et al 2014a b Zhao et al 2005 Cao et al 2013 JianNong et al 2011 Charles et al 2014 In this paper we wish to analyze the focusing property of the phase modulated cylindrically polarized annular multi Gaussian beam CVAMB tightly focused with high NA lensIn conclusion a novel method for demonstrated the effect of phase modulation on the intensity distribution on tight focusing of cylindrically polarized annular multi Gaussian beam in the focal region of high NA lens using Vector diffraction theory We presented possible design of complex phase filter to achieve multiple focal spot and focal hole segments which finds wide applications in optical tweezers micromanipulation of high and low refractive index particles microscopy and optical storageOpen AccessThis article is distributed under the terms of the Creative Commons Attribution 40 International License http//creativecommonsorg/licenses/by/40/ which permits unrestricted use distribution and reproduction in any medium provided you give appropriate credit to the original authors and the source provide a link to the Creative Commons license and indicate if changes were made
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