3D structured Bessel beam polarization and its application to imprint chiral optical properties in silica
Jiafeng Lu, Mostafa Hassan, François Courvoisier, Enric Garcia‐Caurel, François Brisset, Razvigor Ossikovski, Xianglong Zeng, B. Poumellec, Matthieu Lancry
Abstract
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 in femtosecond laser direct writing. Existing polarization-shaping techniques, however, only focus on their manipulation in the transverse plane of light beams, i.e., 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 slowly evolves along the focus (typ. 90° within 60λ). Such a “helically polarized” Bessel beam allows imprinting “twisted nanogratings” in SiO2 glass which result in an extrinsic optical chirality at a micrometric scale and own a high optical rotation. Our work provides new perspectives for three-dimensional polarization manipulation and insights into applications in structured light, light–matter interaction, and chiral device fabrication.