Propagation And Modulation Of Circular Airy Vortex Beams In Free Space

Light waves have physical dimensions such as amplitude,phase,polarization and frequency.A new light field can be generated by adjusting each physical dimension of light waves.As one of the important research results of light field manipulation,circular Airy vortex beam(CAVB)has the characteristics of self-focusing,self-reconstruction and selfbending of Airy beam,and also has the characteristics of vortex beam carrying orbital angular momentum,so it has a wide application in optical communication,particle manipulation,optical imaging and optical processing.The optical field manipulation based on CAVB can greatly improve the flexibility of beam applications in these fields,so as to promote the technical development and progress in related fields.In this paper,Fourier space spectral filtering function and angular phase function are used to modulate circular airy vortex beams,and the transmission characteristics of Fourier space modulated and angular modulated circular Airy vortex beams in free space are studied.Specific research contents are as follows:1.The spectral filtering function is used to modulate circular Airy vortex light from Fourier space,and the transmission characteristics of the modulated beam in free space are studied.The selected spectral filtering functions include S-type function,Gaussian function and cosine periodic function.Different spectral filtering functions can be used to modulate the optical field in various ways.The S-type function modulation method can improve the sudden self-focusing ability of the circular Airy vortex beam.The Gaussian function modulation method can control the autofocusing characteristics of the beam more varied,and the Gaussian or Airy distribution field can be obtained in the focal plane.The cosine function modulation can modulate periodically the frequency spectrum,so as to flexibly control the number of focal points.2.The angular phase modulation function is introduced to adjust the intensity of the light field in the initial plane,and the transmission characteristics of the modulated beam in free space are studied.The selected angular phase function includes sector function and grafting function.Any angular phase modulated circular Airy vortex light can be unfolded into a superposition of a series of standard circular Airy vortex beams.Sector function modulation can control the focus position of circular airy vortex beam in the focal plane.When a circular Airy vortex beam is modulated by grafting function,the open or closed loop distribution of the cross section optical field can be controlled by the topological charge symbol of the grafted vortex beam,and the position of the focal plane focus can be controlled.The evolution process of light field modulated by angular phase function is explained from the perspective of energy flow.The light field manipulation method proposed in this paper can be used to control the transmission track,focal spot intensity,number of focal points and location of focal points.Therefore,the modulated circular Airy vortex beams show excellent application potential in optical tweezers and optical motors.