Creating 3D polarization structures and grafted vortex beams with flat optics

Structured beams with controlled polarization profiles have diverse applications, including information encoding, display, medical and biological imaging, and manipulation of microparticles. The emergent ultrathin optical devices consisting of planar nanostructures, so-called metasurfaces, have shown much promise for creating 3D polarization structures and grafted vortex beams. We experimentally demonstrate colour-selective three-dimensional (3D) polarization structures and grafted perfect vortex beams (GPVBs) with a single metasurface. Colour and phase multiplexing and polarization rotation are used to create various 3D polarization knots. Various superpositions of GPVBs with different combinations of topological charges in four channels can realize asymmetric singularity distributions in the resultant beams. Our research findings may be of interest to many practical applications such as vector beam generation, virtual reality, volumetric displays, singular optics, and quantum science.

References
1- Y. Intaravanne, R. Wang, H. Ahmed, Y. Ming, Y. Zheng, Z. Zhou, Z. Li, S. Chen, S. Zhang and X. Chen*, Color-Selective Three-Dimensional Polarization Structures, Light: Science & Applications 11, 302 (2022).
2- H. Ahmed, Y. Intaravanne, Y. Ming, M. A. Ansari, G. Buller, T. Zentgraf, and X. Chen*, Multichannel superposition of grafted perfect vortex beams, Advanced Materials 34, 2203044 (2022).
3- R. Wang, Y. Intaravanne, S. Li, J. Han, S. Chen, J. Liu, S. Zhang, L. Li, and X. Chen*, Metalens for generating a customized vectorial focal curve, Nano Letters 21, 2081 (2021).