Manipulation Of Optical Focal Field With Transmissive Metalens And Its Applications

The manipulation of light field is always an important research target in the field of optics.In traditional optics,the phase accumulated by light wave propagating in medium can be used to control the polarization state and phase of light field.However,the refractive index of the existing materials in nature is limited,and most of the optical systems which use the change of the propagation path of light wave in the existing materials to realize the optical control are massive.On this basis,a new method based on optical metasurface is proposed.The optical metasurface is a two-dimensional array of sub wavelength scatterers,which can be used to control different characteristics of light(phase,polarization,intensity,etc.).The subwavelength scatterer can modify the incident light.Therefore,by designing different unit structures,the optical characteristics of the incident light can be different from that of the incident light.Because of its excellent performance,this new structure has attracted a lot of attention since its appearance,which is also the main research content of this paper.The main innovation of this paper is to study the influence factors of nanoscale groove type metasurface on the excitation surface plasmon light field,to design an incident chiral dependent metasurface,and to generate vortex light with controllable topological charge.By adjusting the orientation angle of the nanoscale groove,the metasurface can only respond to a certain chirality incident Light.This paper mainly include the following work:1.Based on the theory of Huygens Fresnel and the principle of field superposition,the influence of various parameters on the optical field control is analyzed.The electric field near the center of the hypersurface structure,the structure of the metasurface and the structure of the element are obtained The analytic expression between the angle of incidence and the spin of incident light.2.The physical simulation model of incident light and metasurface is established.Based on the metasurface,the radial light generator,vector beam generator,spin dependent vortex light generator and orbital angular momentum discriminator(OAM)are designed.These new optical devices realize the generation of special beams and the detection of vortex field.