Focal shift of radially polarized bessel-modulated gaussian beam by phase shifting

Xiu-Min Gao,Han-Ming Guo,Song-Lin Zhuang,Jian Wang,Ming-Yu Gao,Song Hu

doi:10.4236/ns.2009.13031

Xiu-Min Gao, Han-Ming Guo + Show 4 more

Open Access

https://doi.org/10.4236/ns.2009.13031

Copy DOI

Abstract

Focal shift of radially polarized Bessel-modu- lated Gaussian (QBG) beam by phase shifting is investigated theoretically by vector diffraction theory. The phase shifting distribution is the function of the radial coordinate. Calculation results show that intensity distribution in focal region can be altered considerably by the topo- logical charge of QBG beam and the phase pa-rameter that indicates the vary degree of the phase shifting along radial coordinate. Topolo- gical charge induces the focal shift in trans-verse direction, while phase parameter leads to the focal shift along optical axis of the focusing system. More interesting, the focal shift may be incontinuous in certain case.

Highlights

Since Caron and Potvliege introduced a novel class of beam expressed in cylindrical coordinate system recently, namely, the Bessel-modulated Gaussian beams with quadratic radial dependence (QBG beam) [1], QBG beam has attracted much attention [2,3,4,5,6,7]
From all above focal pattern evolution, we can see that Topological charge induces the focal shift in transverse direction, while phase parameter leads to the focal shift along optical axis of the focusing system
The phase shifting distribution is the function of the radial coordinate

Summary

INTRODUCTION

Since Caron and Potvliege introduced a novel class of beam expressed in cylindrical coordinate system recently, namely, the Bessel-modulated Gaussian beams with quadratic radial dependence (QBG beam) [1], QBG beam has attracted much attention [2,3,4,5,6,7]. Belafhal and Dalil-Essakali studied the propagation properties of QBG beams through a unapertured optical paraxial ABCD system [4]. Almost all QBG beams in above previous papers are in scalar a form, which means the polarization property of optical field is not considered. Laser beam with cylindrical symmetrical polarization have attracted many researchers recently because the electric field in focal region of such cylindrical vector beam has some unique properties [13,14,15,16]. The present paper is aimed at studying focal shift of radially polarized QBG beam by vector diffraction theory.

PRINCIPLE OF THE FOCUSING RADIALLY POLARIZED QBG BEAM WITH PHASE SHIFTING

B Jm r2 02

RESULTS AND DISCUSSIONS

CONCLUSIONS