This Demonstration compares the axial and radial field intensities in the focal plane of a radially polarized (axicon) laser beam with increased focusing or, equivalently, as the diffraction angle is increased. Such a beam has two electric
This Demonstration compares the axial and radial field intensities in the focal plane of a radially polarized (axicon) laser beam with increased focusing or, equivalently, as the diffraction angle is increased. Such a beam has two electric field components: axial (along the propagation direction) and radial (transverse to the propagation axis). When the beam is focused to a spot size smaller than would be allowed by the paraxial approximation, it develops a pencil-like axial focus within which the intensity increases (with further focusing) at the expense of the radial intensity.
Using the parameters of a Gaussian beam propagating along the axis of a cylindrical coordinate system, a radially polarized laser beam may be shown to have two electric field components: axial and radial. For tight focusing (e.g., to a spot size that is small compared to a wavelength) the paraxial approximation fails to accurately describe the fields. The so-called "truncated-series representation" is a better candidate for modeling the field components and intensity distributions. Within this descr