Study On Self-healing Properties And Applications Of Laser Beams

When some laser beams are affected by obstacles,due to the characteristic of the beam itself,the influence of obstacles on the beam will gradually decrease or even disappear on propagation.In academic circle,this property of the beams is called as self-healing property.After more than 30 years development,the research on the self-healing property of laser beams has become one hot topic in the field of light manipulation,transmission and application.Many scholars have made contributions to the research of self-healing properties.At present,the self-healing properties of laser beams have been successfully applied in the optical tweezers,microscopy,wireless optical communication and so on.It can be predicted that the application of self-healing properties will be further increased.Based on that,we carried out our work.Because not all types of laser beams have self-healing properties,one research line is to discuss the self-healing properties for different types of beams in detail.In addition,the self-healing property is also a general concept.It normally refers to the self-healing of the beam intensity distribution.However,some recent works showed that other degrees of freedom,e.g.the polarization state of the beam,can also achieve self-healing.Therefore,the generalization of self-healing on other physical degrees of freedom of beam has become more and more meaningful.In this thesis,based on Wolf's coherence and polarization theory and the generalized Huygens-Fresnel integral formula,we first studied the propagation and the self-healing process of the radially polarized Gaussian Schell-model beam.We derived the analytical expression of its cross-spectral density matrix in receiver plane when the beam is blocked by an opaque obstacle in the source plane.The numerical results showed that the radially polarized Gaussian Schell-model beam has self-healing property,and we discussed the disturbed propagation process of this beam in detail.After that,we studied the propagation and self-healing process of beam's spatial coherence of scalar Gaussian Schell-model beams.We derived the analytical expression of this beam's cross-spectral density function and calculated the beam's degree of coherence in receiver plane when the beam is corrupted by a transparent turbid medium in the source plane.The numerical results showed that the spatial coherence distribution of the beam also has self-healing property.Finally,as an application of self-healing property of beam's spatial coherence,we have successfully applied the self-healing property of the beam's spatial coherence to ghost imaging technology.Both the experimental results and the numerical simulation results showed that the imaging quality of disturbed ghost imaging can be improved by using the self-healing properties of the partially coherent beams.My study contents and results will provide reference and help for the research and application of optical imaging,beam propagation,optical tweezers technology,ghost imaging technology and so on.