Manipulating the magnetization focal patterns using complex phase filters

Abstract

Based on vector diffraction theory and inverse Faraday effect, the light induced magnetization distribution of a tightly focused azimuthally polarized Bessel-Gauss beam superimposed with a helical phase and modulated by an optimized multi belt complex phase filter (MBCPF) is analyzed numerically. It is noted that by adjusting the radii of different rings of the complex phase filter, one can achieve many novel magnetization focal distributions, such as sub-wavelength scale (0.29λ) and super-long (71λ) pure longitudinal magnetic probe and magnetization chain composed of nine, six and four magnetic spots of sub-wavelength scale. The authors expect that these results pave the path for fabricating magnetic lattices for spin wave operation, multiple atoms or magnetic particle trapping and transportation, confocal and magnetic resonance microscopy, as well as multilayer ultrahigh density magnetic storage.Keywords: inverse Faraday effect, high NA lens, multi belt complex phase filter, azimuthally polarized Bessel-Gauss beam.