Digital Control And Measurement Of Characteristics Of Airy Beam

As a kind of structured light field,Airy beam has great potential in many fields due to its unique characteristics,and has become a hot research topic at home and abroad in recent years.The Airy beam is a special solution of the Schr?dinger equation under the condition of the paraxial condition.The theory and experiments show that the solution has the singular characteristics of no diffraction,selfaccelerating and self-healing,which makes it have broad application prospects in microscopic manipulation,plasma bending channel,multi-beams self-focusing,high-precision imaging,photoelastic and many other fields.In order to meet the needs of practical application in different fields,different forms control of Airy beam have became research hotspots in this field.The current research mainly focuses on the control of transmission trajectories,but the control ranges of existing methods are usually small,and these studies require to move the experimental device during the experiment,and the translation of detector is needed to measure the Airy beam's propagation trajectory,causing inconvenience and a large error.In view of the above problems,this paper proposes a new digital control technology to control Airy beam.Firstly,in view of the problem that the range of previous control means is small,the Fourier transform displacement theorem is used to write digital phase shift into the cubic phase in frequency domain to make corresponding displacement in the spatial domain.The initial surface position of the Airy beam is adjusted,and the subsequent propagation trajectory is calculated.The result shows that the shape of the trajectory does not change,but the overall translation occurs in space.Then,based on the angular spectrum theory,the phase factor with the propagation distance z is written into the cubic phase diaphragm to obtain the angular spectrum form corresponding to the Airy beam at different propagation distances,and then the inverse Fourier transform can be realized by using the lens.The light field corresponding to different propagation distances is obtained in fixed back focal plane of lens,that is,the propagation distance is digitized.Based on this method,the self-acceleration characteristics of Airy beam were measured.The theoretical value is consistent with the experimental results.In addition,by changing the parameters of the phase diaphragm,the control of beam's scale and the transverse acceleration is realized in a fixed plane.The calculation and simulation results show that the process can change beam's energy flow distribution,thus,change generated gradient force,it can be used in efficient and fast particle handling and cleaning.By writing the phase modulation function of the lens into the phase diaphragm,the Fourier lens can also be digitized,and the parameters can be changed to control the parameters such as the beam size of the Airy beam.Finally,a plurality of cubic phase diaphragms are combined to produce an Airy beam array.By adjusting the orientation of the phase diaphragms,the main lobes are directed to the center of the array,thereby,generate a self-focusing array,and the propagation distance is changed digitally to achieve the control of the focusing process,the beam intensity distribution in the process is analyzed,and the intensity of the center point is greatly enhanced,which proves the feasibility of the scheme.