Study On Propagation Properties Of Vector Circular Airy Beams

Because of Airy beam’s special non-diffraction,self-bending and self-healing properties,it has been used in many fields,such as optical micromanipulation,plasmas,optical bullets and electron beams.The circular Airy beams have a unique abruptly self-focusing effect with the distribution form of one-dimensional Airy beam in the radial direction.The energy of this beam sharply increases when it reaches the target,resulting in a stronger gradient force at the focus and a more stable capture of microscopic particles than conventional Gaussian beams.The circular Airy beams present a one-dimensional Airy beam distribution in the radial direction.The circular Airy beams bend toward the optical axis during propagation,and the light intensity increases rapidly near the focus point in the absence of a focusing element.The self-focusing effect of the circular Airy beams is the spontaneous behavior of the beams and the result of the propagation of Airy beam along a parabolic path.By means of the geometrical optical analysis results of twodimensional Airy beam,a series of rays are emitted from the incident plane in different directions,and the trajectory formed by the main lobe is the envelope of this beam,that is,all the outgoing rays are tangent to the trajectory of the main lobe.Therefore,the main lobe at a specific propagation length is generated by the contribution of the corresponding side lobe on the incident plane.This can also be used to explain its selfhealing property.For circular Airy beams,the main contribution of the light intensity at the focal point comes from a specific position in the incident plane,corresponding to a specific position of the wave vector in the Fourier space.In this paper,the propagation characteristics of vector-circular Airy beams are discussed,including linear polarization,radial polarization and angular polarization.Based on the band-pass filter,a new type of circular Airy beams is designed to obtain a better light intensity enhancement effect.Firstly,the specific position that contributes most to the intensity of the focus light is found on the incident plane through geometric optics analysis.Then the position of the corresponding wave vector in the Fourier space can be obtained.The angular spectrum will be concentrated at the specific position of the wave vector by introducing a bandpass filter to modulate the circular Airy beam in Fourier space.In this way,the modulated circular Airy beams will be concentrated on the specific position in the initial plane.The angle spectrum theory was used to analyze this new type of circular Airy beams and compared with the common circular Airy beams.The results show that the light intensity at the focal point of the circular Airy beams with linear polarization,radial polarization and angular polarization is greatly improved.At the same time,the light spot after the aggregation point is also eliminated,and there is only a large light intensity around the focal point in the whole propagation surface.