Abstract
The intensity distributions near the focal point for tight focusing of azimuthally polarized Laguerre–Gaussian beam including higher order modes are calculated based on vector diffraction theory. For higher order as well as the fundamental lower order mode A-TEM01*, a small focal hole at the centre is obtained for the focusing under high NA lens. In a limit of NA = 0.95, the higher order A-TEMp1* mode beams of p = 1, 2, 3, 4, 5 and 6 are established numerically in detail. It is observed that one of the higher order mode A-TEM51* generates some interesting results. And it is also observed that the intensity distribution of the different mode has little variation among the degree of truncation (β) of the input beam beside the pupil. This work is important for optical manipulation, optical data storage, micro-machines and optical trapping applications for low refractive index particles.
Highlights
Generation and application of optical tube beams are one of the very fascinating subjects in optics
The intensity distributions near the focal point for tight focusing of azimuthally polarized Laguerre– Gaussian beam including higher order modes are calculated based on vector diffraction theory
This work is important for optical manipulation, optical data storage, micro-machines and optical trapping applications for low refractive index particles
Summary
Generation and application of optical tube beams are one of the very fascinating subjects in optics. The higher order mode R-TEM11* (doublering-shaped) radially polarized beams can successfully decrease the focal spot size by p phase shift due to the destructive interference between the inner rings as well as the. A well created outstanding focal spot, where the spot size, focal depth and the side lobe intensity are 0.41 k, 9.53 k and 16.35 % by tight focusing of a higher order radially polarized beam with the 17-belt binary phase pupil filters [15]. For higher order azimuthally polarized modes with a single-ring-shaped A-TEM01* mode beams form a small focal hole at the focal point below the high NA focusing condition.
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