Airy beams have been attracting considerable interest because of their unique properties, including transverse acceleration, nondiffraction, and self-reconstruction. In most experiments, Airy beams are generally induced by continuous cubic phase patterns generated using a phase-type spatial light modulator(SLM). However, a phase-only SLM has some intrinsic disadvantages, such as large pixel size, low resolution, and low laser damage threshold. To solve these problems, binary-phase elements may be a good method for generating Airy beams because of low cost and easy fabrication.

Researchers at Shanghai Institute of Optics and Fines Mechanics (SIOM/China) theoretically and experimentally study the physical process of Airy beams induced by binary phase patterns combined with a slope factor. Theoretical simulations show that the binary phase patterns generate a pair of symmetrically inverted twin Airy beams. The slope factor can regulate the spacing between the two Airy beam peaks, decrease the error induced by the binarization process, and adjust the position of the focus formed by the twin Airy beams. The experimental results are consistent with the theoretical ones.[OPTICS LETTERS ,38(8),1286-1288]

Compared with the common Airy beam, the twin Airy beams possess more attractive properties. First, observing the acceleration in free space is much easier. There is no need to measure the relative deviation of the main lobe of the Airy beam from the optical axis. Second, there is a controllable focus, and the position of the focus can be altered by introducing a slope factor. In addition, binary phase patterns are low cost and can be easily fabricated, indicating their large scale potential applications.