The Transformation Process Of Phase Singularities Of Laser Beams Near The Focal Plane

With the development of Laser technology, the domain of modern optics is enlarging. Such as, singular optics is a new branch of modern optics. Recently, singular optics has been studied by many experts, due to its universality and practicality. For example, it includes the singularities of homochromy light, the singular behaviors of polychrome spectrum and the phase singularities of partially coherent beams et al. This dissertation is just a small segment of singular optics. In this dissertation, the transformation process of the phase singularities of homochromy beams near the focal plane is studied. The main work of the dissertation is as follows:1. The creation-annihilation process of phase singularities of super-Gaussian beams in the focal plane is studied within the framework of the scalar paraxial approximation. That of a new kind of flat-topped beams introduced by Li is also studied. It is shown that both of the two beams have the similar process. By suitably varying the truncation parameter, the phase singularities reorganize themselves, which leads to the annihilation of singularities in the focal plane, the creation of singularities outside the focal plane and subwavelength structures. Apart from the truncation parameter, the beam order of flat-topped beams additionally affects the spatial distribution of phase singularities. But the rates of the creation-annihilation process of phase singularities of the two kind beams are different.2. The transformation process of the phase singularities near the focal plane under the influence of the spherical aberration is studied. It is shown that the annihilation processes of the phase singularities near focal plane are different owing to the sign of the spherical aberration, when the phase singularities near focal plane have created with suitable truncation parameter.