Research On The Design And Characterize Methods Of A Subwavelength Lens Based On SP

With the rapid development of nanotechnology and micro-nanofabrication technology, nano-optics with its unique optical properties has played an increasingly important role in many research areas. The ever-increasing interest to explore the optical world at nanoscale has presented the demand to manipulate visible light in the subwavelength scale. For this very purpose, decreasing the size of optical lenses to micron and submicron scale is needed. However, due to diffraction limit, the efforts are hindered when the size of the lens approaches the wavelength of light. The Surface plasmonic devices are the potential to overcome the diffraction limit. SP originating from collective oscillations of free electrons at a metal-dielectric interface. The lens based on SP have been particular interest in nano-optic device research, these surface Plasmon-based lenses can achieve subwavelength-scale focal zones. Plasmonic lenses have proven to be useful in numerous applications such nanofabrication, nanophotonic circuits, and circular polarizer analyzers.In this paper, we propose and demonstrate experimentally a planar plasmonic lens consisting of metal nano-slits with variant amount of filled SiO2 material. The plasmonic lens is fabricated and its functionalities have been examined by a scanning near-?eld optical microscope which can offer optical resolution down to ~100nm scale. Two focal spots have been observed by scanning near-?eld optical microscope mapping at different height above the sample’s surface, which is consistent with the numerical calculation results.The principle of the surface plasmonic lens. Based on the basic properties of the surface plasmonic exists in metal- insulator-metal, the propagation of surface plasmonic characteristics are analyzed to find the factors which will affect the transmission of electromagnetic in metal waveguide.Design and optimize the parameters of the surface plasmonic lens. By discussing the physical origin of the transport properties of sub-wavelength waveguides with the dielectric constant of electromagnetic waves, we propose a planar plasmonic lens consisting of metal nano-slits with variant amount of filled SiO2 material, the SiO2 is used to manipulate the delay of the SP, a finite analyses method is applied to build a model to simulate and optimize the parameters.Study on the methods of characterizing the plasmonic lens. To investigate the plasmonic lens focusing effect, A simple experiment of double slits interference was done to verify the validity of phase modulation induced by filled SiO2.With the facilitate of scanning near-field microscopy, we have detected the focusing spot of the plasmonic lens. Both the experiment group and the control group lens are produced and experimentally investigated. Focusing spots of plasmonic lens at focal length about 2μm and 5μm are observed and consistent with simulation results. The experimental errors are analyzed, the focusing consistent with the numerical calculation results verify the reliability of this characterization methods.