Generation And Propagation Characteristic Of Airy Vortex Beams

In recent years,Airy beam with the properties of non-diffraction,self-healing and its unique feature of self-bending,has triggered an upsurge of research in optical field.Such beam is widely used in application of particle cleaning and trapping,plasma channels,light bullets and medical treatment.Vortex beam with a helical phase distribution,has a dark core with zero-intensity,enabling to capture particles without damage.It is of great importance in biomedicine field for reducing cell damage.Meanwhile,vortex beam with orbital angular momentum,can capture particles and rotate them.These advantages of vortex beam make it of great value in research of optical micro-manipulation and quantum communication.Based on the respective characters of Airy beam and vortex beam,we propose the Airy vortex beams which exhibit the properties of two of them.The main works of this paper are as follow:Firstly,the Airy vortex beams can be generated by superimposing a helical phase on the cubic phase.We can obtain diverse Airy vortex beams at the initial field by changing the dislocations between the cubic phase and the helical phase.The simulation and experiment have verified that the optical vortex has no influence on the propagation of Airy beam,and the main lobe of Airy beam still follows the parabolic trajectory during propagation.Meanwhile,the distance between the optical vortex and Airy beam gradually increases during forward propagation.Secondly,in order to resolve the issue of Airy beam with its asymmetrical energy distribution,a symmetrical Airy beam is proposed due to its self-bending.This beam is obtained by taking the absolute value of the cubic phase mathematically.Embedding the helical phase into the absolute cubic phase in different positions,we can acquire two forms of symmetrical Airy vortex beams,on-axis and off-axis.The simulation and experiment have certified that the symmetrical Airy vortex beams exhibit auto-focusing during propagation.The on-axis symmetrical Airy vortex beam has a dark core due to the optical vortex.Besides,the beams rotate at the initial plane.While the dark core of off-axis symmetrical Airy vortex beams appears during propagation.Thirdly,to obtain tunable Airy vortex beams at the initial plane,we introduce a linear factor c on the absolute cubic phase.With the value of linear factor c greater than zero,the main lobes of Airy beam propagate inward along the axis.However,the main lobes of Airy beam propagate away from the axis when c is less than zero.Finally,the influences of three parameters,namely decaying coefficient,scale parameters and wavelength are discussed.The larger decaying coefficient is,the weaker energy of the obtaining beams can be.The larger scale parameters are,the smaller bending degree and the narrower width of the beams will be.And with a large wavelength,the trajectory of the beams is quite steep and the self-focusing position is moving forward.