Presentation Information
[15a-S4_201-9]Influence of the Truncation Parameter on the Tight Focusing of C-point Singularities
Sushanta Kumar Pal2, 〇(D)Rudrashis Panda1, Rakesh Mohan Das1 (1.KIIT University, 2.SOA University)
Keywords:
optical vortex,polarized beam,electromagnetic field analysis
Structured light beams containing polarization singularities have enabled significant progress in super-resolution imaging, optical communications, optical activity measurements, and atmospheric optics. At a polarization singularity, one or more parameters describing the state of polarization (SOP), such as azimuth or handedness, become undefined. These singularities occur in optical fields with spatially varying polarization distributions. In ellipse fields, where the local SOP is predominantly elliptical, the corresponding singularities are known as C-points, at which the polarization state becomes circular. Recently, tight focusing of polarization singularities has attracted significant interest. In this article, we investigate the tight focusing of a C-point polarization singularity for three truncation parameters b=1, 2, and 4. The truncation parameter b quantifies the degree of aperture filling and is defined as the ratio of the pupil (aperture) radius to the beam waist at the entrance pupil. For our study a C-point singularity is generated through the coaxial superposition of right- and left-circularly polarized beams carrying orbital angular momenta of 1 and 0, respectively. This composite beam is then tightly focused using a high-numerical-aperture lens (NA=0.96). The simulation results demonstrate that the focal-plane intensity distribution becomes increasingly circularly symmetric with increasing truncation parameter.