The Propagation Of Airy Beam In Free Space And Photorefractive Medium

Diffraction is one of the basic characteristics of optical beams.When the optical beams transmit in vacuum or in a homogeneous medium,the beams will widen and the energy will diverge due to the diffraction.But in the optical field,there is a special kind of beam,which is non-diffraction,and the most famous one is Bessel beam.Bessel beam has the properties of non-diffraction and self-healing,which lays the foundation for the study of non-diffraction beams.However,as a new type of non-diffraction beam,the Airy beam has the property of self-accelerating as well as non-diffraction and self-healing.The Airy beam has great application value in the fields of particle manipulation,optical bullets and plasma curved channels.In this paper,we investigate the propagation properties of Airy beam in free space and photorefractive medium by numerical simulation.The main contents and achievements are as follows:1.The effects of transverse scale,wavelength and exponential aperture factor on the propagation of Airy beams in free space are studied.The FWHM of Airy beam main lobe will grow up with the transverse scale increasing,and the self-accelerating will slow down.With the increase of wavelength,transverse self-accelerating of Airy beam will speed up.The influence of exponential aperture factor is mainly manifested in that the larger the exponential aperture factor,the faster the side lobe energy attenuation,and finally the Airy beam will become the like-Gauss beam,which cannot maintain the self-acceleration characteristics in the transmission.2.The propagation of Airy beam in photorefractive medium is investigated.With the self-defocusing nonlinearity effect,Airy beam will be broadened,but can still maintain the original intensity distribution and self-acceleration characteristics;however with the self-focusing nonlinearity effect,the intensity distribution of Airy beam and self-accelerating characteristics will be destroyed.When photonic lattice induced in the photorefractive medium and Airy beam main lobe launched in the lattice site,with the appropriate external bias voltage and lattice strength,the energy will be bound in the lattice site,it will limit the self-accelerating properties of Airy beam.When the positive or negative defects are added to the lattice site,the positive defects will make the beam energy focus and the negative defects will make the main lobe energy spread to the near-by lattice sites.3.We finally study the self-healing characteristics of two dimensional Airy beam withdifferent regions blocked.When the main lobe and the internal areas blocked,the intensity distribution of the Airy beam will be reconstructed after a certain propagation distance.However,the Airy beam will not be reconstructed only the main lobe left.In this paper,we introduce the Gauss noise to study the self-healing characteristics of Airy beam in the noisy environment.It is shown that the partially blocked Airy beam can be healed after a certain distance,and it also has certain robustness.