3D structured Bessel beam polarization and its application to imprint chiral optical properties in silicaPolarization plays crucial role in light-matter interactions; hence its
overall manipulation is an essential key to unlock the versatility of light
manufacturing, especially in femtosecond laser direct writing. Existing
polarization-shaping techniques, however, only focus on the manipulation in
transverse plane of a light beam, namely a two-dimensional control. In this
paper, we propose a novel passive strategy that exploits a class of femtosecond
laser written space varying birefringent elements, to shape the polarization
state along the optical path. As a demonstration, we generate a
three-dimensional structured Bessel beam whose linear polarization state is
slowly evolving along the focus (typ. 90 degrees within 60 lightwave periods).
Such a "helical polarized" Bessel beam allows imprinting "twisted nanogratings"
in SiO2 resulting in an extrinsic optical chirality at a micrometric scale,
which owns a high optical rotation. Our work brings new perspectives for
three-dimensional polarization manipulations and would find applications in
structured light, light-matter interaction and chiral device fabrication.
arxiv.org