Subwavelength Metal Structure In High Resolution Focusing Imaging Applications

As one of important research direction of optics and materials, nanophotonics havebeen attracted many scientists to work on it. Moreover, Surface plasmon as mostimportant part of nanophotonics, many people focusing their attraction on it. Plasmoniclens, which has the potential ability to break through the traditional diffraction limithave been investigate in this paper. Three phase modulation ways have been studied:one is depth modulation; another one is width modulation; as well as depth-widthhybrid modulation. From theory and experimental aspect, we studied the influence ofthree modulations to the super focusing characteristic of plasmonic lens. And we foundthat width modulation has the best performance of the super focusing. The maincontributions of this paper are listed as follows:First of all, a plasmonic lens has been designed which looks like traditional Fresnelzone plate lens. However, it has totally different parameters and has long depth of focusand small FWHM. And the plasmonic lens can break through diffraction limit becauseof the surface plasmonic was exited on the surface of metal and those sub-wavelengthcorrugations which can modulate the light.Secondly, the way of fabricating plasmonic lens-focusing ion beam millingtechnology has been introduced in this paper. As well as near field scanning microscopy,the way to investigate the plasmonic lens also been introduced in this paper.Finally, a theory model of plasmonic lens has been studied use FDTD simulation.The simulation result claims that the width modulation has best performance which isthe same to the experimental result. The late one has been studied use near filedscanning optic microscopy. The width modulation plasmonic lens can obtain176nmFWHM in theoretically and390nm FWHM in experimentally.