Generating radially polarized beams interferometrically

TLDR

The techniques are based on the linear combination of orthogonally polarized beams with tailored intensity and phase profiles. The paper describes two interferometric techniques to convert a linearly polarized laser beam into a radially polarized beam with uniform azimuthal intensity. The authors use two interferometric methods: one combines linearly polarized beams with tailored intensity profiles from a modified laser or apodization filter, and the other employs circularly polarized light with a spiral phase delay plate to generate the required phase profile. The resulting radially polarized beam achieves an extinction ratio of –21.7 dB with azimuthal intensity variations below ±12 %, and when focused provides a net longitudinal field suitable for particle acceleration and other applications.

Abstract

Two interferometric techniques for converting a linearly polarized laser beam into a radially polarized beam with uniform azimuthal intensity are described. The techniques are based on the linear combination of orthogonally polarized beams, which have tailored intensity and phase profiles. Linearly polarized beams with intensity profiles tailored using a modified laser or an apodization filter are combined in separate experiments to produce radially polarized light. A beam with an extinction ratio of -21.7 dB and azimuthal intensity variations of less than +/-12% is produced using the modified laser output. The second technique uses circularly polarized light and a unique spiral phase delay plate to produce the required phase profile. When focused, a radially polarized beam has a net longitudinal field useful for particle acceleration and, perhaps, other unique applications.