3D structured Bessel beam polarization and its application to imprint chiral optical properties in silica

Polarization plays a crucial role in light–matter interactions; hence its overall manipulation is an essential key to unlock the versatility of light manufacturing, especially femtosecond laser direct writing. Existing polarization-shaping techniques, however, only focus on their transverse plane beams, i.e., two-dimensional control. In this paper, we propose novel passive strategy that exploits class written space varying birefringent elements shape polarization state along optical path. As demonstration, generate three-dimensional structured Bessel beam whose linear slowly evolves (typ. 90° within 60λ). Such “helically polarized” allows imprinting “twisted nanogratings” SiO2 glass which result extrinsic chirality at micrometric scale and own high rotation. Our work provides new perspectives for insights into applications light, interaction, chiral device fabrication.