Creation of Ultra-Long Pure Magnetization Needle Bycircularly Polarized Beam with A Ternary Optical Element

Based on the vector diffraction theory and Inverse Faraday Effect, the light induced magnetizationneedle is generated by tightly focusing a circularly polarizedbeam that is modulated by a self-designed ternary hybrid (phase/amplitude) filter (THF). Both the phase and the amplitude patterns of THF are judiciously optimized by the versatile particle swarm optimization (PSO) searching algorithm.It is noted that by optimizing to produce an ultra-long pure magnetization needle with lateral sub-wavelengthscale and a super-long spherical magnetization chain with three-dimensional super resolution. The present work regarding these super-resolutionmagnetization patterns is of great value in high density all-optical magnetic recording, atomictrapping as well as confocal and magnetic resonance microscopy.