Research Of Generation,Detection And Manipulation Of Optical Vortex Beam

Vortex is a widespread physical phenomenon.The optical vortex in optics generally refers to a special light field with a spiral phase wavefront exp(il?),in the central point of which there exits a phase singularity resulting from the uncertain phase for the center,therefore,the intensity of optical vortex is like a ring with a dark hollow.A lot of attention and research have been poured into the study of optical vortex beam in the field of micronano manipulation,nonlinear optics,and optical communications recent years.Surface plasmon polaritons(SPP)characterized by local field enhancement and subwavelength confinement is an electromagnetic mode formed by the interaction of free electrons and light on the metal surface which providing new possibilities for optical field controlling.Today,SPP has found application in the field of super-resolution imaging,sub-wavelength focusing,light field control,optical tweezers and so on.The accumulated interaction of light and metamaterials is the basis of threedimensional metamaterials to achieve light field control,which usually leads to a large ohmic loss.Recent years has witnessed more and more research about the twodimensional metasurface which overcomes the defects of Three-dimensional metamaterials mentioned above.Metasurface generally composed of sub-wavelengthsized nanorods,wires,and holes,etc.arranged in some way to form arrays are widely used in beam reshaping,polarization conversion,imaging and other fields because of it characteristic of light field controlling point to point.This thesis mainly studies the generation and manipulation of optical vortex fields,detection of topological charges of optical vortices and deuterogenic plasmonic vortices of plasmonic vortex lens based on metasurface and SPP.The specific research contents are as follows:Firstly,the Bessel-like beams propagating along straight lines and serpentine curves are studied,and the topological charge is regulated during the propagation process.The effect of the calculated initial phase is verified by means of numerical integration calculation.Besides,finite difference time domainmethod(FDTD)is used to simulate the metasurfaces which loads the initial phase and the optical vortex field with different designed topological charges along a specific trajectory are realized as the transmission distance increases.Secondly,an orbital angular momentum detector is proposed which realizes the onchip orbital angular momentum discrimination by excited surface plasmon polaritons of segmented slits.Compared with metasurface and plasmon gratings,the detector with about 10 ?m order is more friendly in processing and manufacturing.By observing the interference pattern,the topological charge of the incident optical vortex can be obtained intuitively without measuring the distance or angle.Finally,deuterogenic plasmonic vortices generated by plasmonic vortex lens is studied and verified theoretically.The most widely accepted theory is that common plasmonic vortex lens can produce vortex field with a certain number of topological charges.However,it is a series of derivative vortex fields with different orders rather than single one that occupies in the surface of the plasmonic vortex lens from the research of this paper.The compound derivative plasmonic vortex fields with different degrees are described mathematically from theory which show a good greement with serveral sets of simulation results by FDTD.This phenomenon is experimentally verifid at last.