Submicron surface plasmon polariton beam splitter based on composite cavity structure

Abstract

The invention discloses a submicron surface plasmon polariton beam splitter based on a composite cavity structure. The surface plasmon polariton beam splitter comprises a metal thin film. A nanometer suture which can penetrate through an upper surface and a lower surface of the metal thin film are arranged on the metal thin film. A nanometer groove is formed on one side of the nanometer suture to form an asymmetric nanometer monolete suture. A metal-medium-metal metal injection molding (MIM) vertical cavity is integrated below the nanometer groove. On an operating wavelength of the beam splitter, a function point (FP) resonant cavity and the MIM vertical cavity are used for nearly manipulating surface plasmon polaritons (SPPs) independently, wherein the FP resonant cavity is formed in the upper half portion of the asymmetric nanometer monolete suture and the MIM vertical cavity is integrated in the FP resonant cavity. Therefore, the submicron surface plasmon polariton beam splitter based on the composite cavity structure has the advantages that SPPs beam splitting can be achieved. The greater advantage is that beam splitting wavelength can be allowed and convenient to adjust. Meanwhile, transverse size can not be increased, and the integrated height can be increased. In a high integration density plasmon polariton return circuit, the submicron surface plasmon polariton beam splitter based on the composite cavity structure has a potential application. The submicron surface plasmon polariton beam splitter based on the composite cavity structure is simple in structure, good in beam splitting performance, high in extinction ratio and capable of providing a design thought for other surface plasmon polariton function components.

Description

technical field [0001] The invention relates to the field of nanophotonics, in particular to a submicron surface plasmon beam splitter based on a composite cavity structure. Background technique [0002] Surface plasmon polaritons (Surface Plasmon Polariton) SPPs are currently a hot spot in nanophotonics research. The surface plasmon is a collective oscillation that exists at the interface between the metal and the medium coupled with the light wave and the free electrons in the metal. It is a special electromagnetic field in the interface bound mode. Its existence can be solved by solving the interface between the metal and the medium. It is obtained from Maxwell's equations under the boundary conditions. The biggest feature of SPPs is that they can localize the light field within the sub-wavelength size at the interface between the metal and the medium, breaking through the diffraction limit of traditional optics. At the same time, they also have a local field enhancement...

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Problems solved by technology

However, these additional grating structures greatly increase the size of the SPPs beam splitter, which is not conducive to high integration

Furthermore, the beam splitting of SPPs can also be realized by covering a layer of dielectric film with a finite thickness on the asymmetric nanometer single slit, but due to the increase of the dielectric film, the transmission distance of SPPs is shortened, and at the same time, the device design and processing costs are reduced. flexibility

Recently, it was proposed to use the different reflective properties of nanogrooves with different sizes to SPPs, that is, to prepare a pair of parallel nanogrooves with different widths to realize submicron beam splitters, but the beam splitting ratio is too low. Only beam splitting ratios of 3:1 and 1:2 are obtained at 650nm and 750nm respectively

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