Recently, the research group of micro/nano-optics and photon integration under the National Key Laboratory for Transient Optics and Photon Technology of our institute, based on photonic spin Hall effect of metalens, realized focusing of left/right-handed circularly polarized light at arbitrary position in 3D space, breaking the focusing symmetry of spin-related light beam as previously reported, and being of important significance for metalens-based optical imaging study. The study was greatly supported by CAS’ strategic leading technology project (Type B) “Large-scale Photon-integrated Chip” and the National Natural Science Foundation. Relevant achievements were published in the Advanced Optical Materials (IF=7.43@2017;SCI Section I) under Wiley on March 5, and reported as a highlight in the manner of Inside Front Cover. The paper title is: Multidimensional Manipulation of Photonic Spin Hall Effect with a Single-layer Dielectric Metasurface.

Left Figure: Front cover of the journal; Right figure: achievements report

Conventional optical lens realizes focusing by regulating incident light phase through glass thickness change. Such lens is large in volume and clumsy. With micro/nano-optics developing, conventional optical lens has become hard to meet requirements of large-scale integration, device miniaturization and more diversified functions. Metalens features a 2D plane lens structure by artificially arranging optical antennas with special electromagnetic characteristics, can realize flexible regulation of parameters of incident light, such as amplitude, phase and polarization, and has important applications in ultra-resolution microscopic imaging, holographic optics and achromatic lens. Metalens breaks through the electromagnetic attribute of conventional optical lens, and its 2D plane structure is easier for processing and integration, providing solutions for miniaturization and integration of optical lens.

The team, based on single-layer metalens structure, realized spin Hall effect of photon, and acquired focusing of left/right-handed circularly polarized light at arbitrary position in space with the effect. Similar to spin Hall effect of electron, photon with reverse spin angular momentum (namely left/right-handed circular polarization) may generate the phenomenon of spin splitting of light beam when transmitted through uneven medium, namely photonic spin Hall effect. The team, making use of the method of combining the nm antenna’s dynamic phase constituting metalens with the Pancharatnam-Berry geometric phase, ingeniously designed the geometric structure and space orientation of nm antenna on metalens, and realized photonic spin Hall effect and independent control of left/right-handed circularly polarized light phase on single-layer metalens, completed focusing of different-spin-state light beams in horizontal and radial directions simultaneously, and enhanced light beam controlling and focusing capacity of metalens. The design features compact structure and strong flexibility, can meet the needs of large-scale integration, device miniaturization and diversified function, and has important applications in full-vector polarization imaging and circular dichromatic spectral detection fields, etc. (By the Key Laboratory) 

Single-layer medium-based metasurface photonic spin Hall effect