Airy optical beams have come out to stir up enormous research interests due to their extraordinary characteristics of self-accelerating, self-healing, and being nearly diffraction free. There are various schemes to generate Airy beams, for instance, using spatial light modulators (SLMs). However, they significantly condense the quality of the generated Airy beams due to the poor phase discretization, as Airy beams possessing specific characteristics need phase profiles with large phase slope. Although lately several plasmonic or dielectric metasurface-based generators provide phase profiles with subwavelength pixelization offering a compact and cost-effective platform, the method based on synchronous manipulation of the amplitude and phase limits the generation efficiency of Airy beams. Besides, most of currently demonstrated metasurface-based Airy beam generators are polarization-sensitive.

To circumvent the above limitations, Prof. Dawei Zhang's group from Engineering Research Center of Optical Instrument and Systems and Ministry of Education and Shanghai Key Laboratory of Modern Optical System, affiliated to "Future Optics" Laboratory lead by Academician Songlin Zhuang and Academician Min Gu, University of Shanghai for Science and Technology, China, has proposed and experimentally demonstrated polarization-independent highly efficient generation of Airy optical beams with dielectric metasurfaces. The corresponding result is published in Photonics Research, Vol. 8, Issue 7, 2020 (Binbin Yu, Jing Wen, Lei Chen, et al. Polarization-independent highly efficient generation of Airy optical beams with dielectric metasurfaces[J]. Photonics Research, 2020, 8(7): 07001148).

This study implements a scheme based on the 3/2 phase-only manipulation by spatially varying the diameter of the dielectric cylindrical unit element of the metasurface, instead of synchronous manipulation of the amplitude and phase. As a result, this scheme has several advantages in the following aspects. First, the transmission of the nano-pillar element is near-unity as the diameter falls in two-thirds of the whole parameter range. Second, a distinct envelope of the resultant Airy beam is molded right away without filtration of the polarization states for the input and output beams. Third, high average generation efficiency of the demonstrated highly deflected Airy optical beams with trivial beam widths is achieved.

Prof. Dawei Zhang and Asso. Prof. Jing Wen believe the presented scheme will open the door for Airy beams to play a vital role in infrared sensing, atmospheric optics, fluorescence imaging, laser fabrication etc. Future work will focus on quantification and tuning the inherent parameters of Airy beams to explore the beams in potentially various and specific applications.

Caption: Polarization-independent highly efficient generation of Airy optical beams with dielectric metasurfaces