Abstract

Light wave is described as a transversal wave by Maxwell equations, i.e., its polarization is always perpendicular to its propagation direction. However, tightly focused radial polarized light has strong longitudinal components, which take about 45% of the total energy in the central lobe when the numerical aperture of the lens is 0.95 [1], and this ratio can increase to 81% after applying a binary optical element shown in Fig.1a, where the energy density of radial component is only about 8% of the longitudinal component, i.e., this beam is substantially a longitudinally polarized beam, as is shown in Fig.1b. This longitudinally polarized laser beam propagates about 4 wavelengths without divergence, with a beam size of about 0.43λ, as is shown in Fig. 1c.

© 2011 Optical Society of America