In 1979, Berry and Balazs firstly observed a nonspreading Airy wave function which is a solution of the quantum mechanical Schrodinger equation. Considering the mathematical correspondence between paraxial equation of diffraction and the Schrödinger equation, Siviloglou et al. demonstrated the accelerating optical Airy beams in 2007.
The accelerating Airy beams possess the well-known ability of maintaining diffraction-free while propagating along a curved parabolic trajectory in the free space. Additionally, the Airy beams exhibits a self-healing feature. Based on these unique features, the Airy beams can possibly have promising applications over numerous challenging fields, such as optical routing, particle manipulation, light bullets, microscopy and plasma physics. Although most studies of the accelerating Airy beams are associated with the optical domain, it is still of great interest to demonstrate such Airy beams in the terahertz (THz) domain.
Prof. Jinsong Liu’s group from Wuhan National Lab for Optoelectronics (WNLO) demonstrates the generation of the accelerating THz Airy beams with a 0.3-THz continuous wave. Two diffractive elements are designed and 3D-printed to form the generation system, which can not only imprint the desired complex phase pattern but also perform the required Fourier transform (FT). They both numerically and experimentally demonstrate the propagation dynamics of the accelerating THz Airy beam and investigate its self-healing property during propagation in the free space. Their observations are in good agreement with the numerical simulations. Such accelerating THz Airy beam could be able to develop novel THz imaging systems and robust THz communication links.
This research is supported by the National Natural Science Foundation of China under grant No. 11574105, 61475054, 61405063, 61177095, the Fundamental Research Funds for the Central Universities under grant No. 2014ZZGH021, 2014QN023, the Wuhan applied basic research project with No. 20140101010009.
Figure. Experimental (left) and simulation (right) results of the finite-energy accelerating THz Airy beam are illustrated. The top row indicates the xz normalized intensity profiles of the Airy beam. (b)-(e) The xy normalized intensity profiles of the experimentally generated Airy beam measured at the dash line positions of the upper image. (g)-(j) The corresponding simulation results at the same detection planes.