Surface plasmon polariton directional coupler independent of polarization and control method thereof

A surface plasmon and directional coupler technology, applied in the field of nanophotonics

Inactive Publication Date: 2015-08-19
PEKING UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, due to the p-polarization-dependent nature of SPPs, it is a serious challenge to directionally couple out SPPs with s-polarized incident light.

Method used

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  • Surface plasmon polariton directional coupler independent of polarization and control method thereof
  • Surface plasmon polariton directional coupler independent of polarization and control method thereof
  • Surface plasmon polariton directional coupler independent of polarization and control method thereof

Examples

Experimental program
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Effect test

Embodiment 1

[0032] As shown in Figure 1, the metal film of the present embodiment, small hole, ridge waveguide and protrusion nanoparticle; Wherein, the thickness of metal film is t, is provided with small hole on metal film; On metal film and is positioned at small hole Two ridge waveguides are arranged symmetrically at both ends, and the width of the ridge waveguide and the width of the small hole can be inconsistent. By adjusting the width w and height h of the ridge waveguide, the ridge waveguide only supports a single SPP mode; in the metal film Protruding nanoparticles are arranged on and on one side of the small hole; the protruding nanoparticles do not completely cover the edge of the small hole, forming a defective small hole structure.

[0033] First, a ridge waveguide is set on the metal film, w=290nm, h=300nm, and the metal film is made of gold film. The field distribution of the SPP mode supported by the ridge waveguide is shown in Figure 1(c). At this time, the incident ligh...

Embodiment 2

[0039] By tuning the structural parameters of the protruding nanoparticles, the p-polarized and s-polarized coupled SPP modes can be separated and propagate in opposite directions. In this example, the width of the protruding nanoparticles was reduced to 60 nm. The corresponding SEM images and details are shown in Figure 4 (a) shown. Other structural parameters of the defective pore structure are as follows: w=260nm, L=560nm, L d =240nm, h=350nm, and ΔL=60nm. The electric field CCD image obtained by the incident light λ=780nm is as follows Figure 4 (b) and (c) shown. It can be seen from the CCD image that the SPP mode coupled by the p-polarized incident light mainly propagates to the right along the ridge waveguide, and the corresponding extinction ratio is about (I R / I L ) p ≈5.1, so the right grating is illuminated as Figure 4 (b) shown. However, the SPP mode coupled by the s-polarized incident light mainly propagates to the left along the ridge waveguide, and t...

Embodiment 3

[0042] In this example, COMSOL Multiphysics is used to calculate the influence of the defective pinhole structure on the SPP mode coupling on the ridge waveguide. The calculation formula, the structural parameters of the ridge waveguide and the small hole are the results obtained from the experimental measurement of the sample shown in Figure 1, and the parameters are w=290nm, L=600nm, h=300nm, ΔL=60nm. Changing the structural parameter w of the protruding nanoparticles d and L d The strength of the obtained SPP mode is as Figure 5 (a) to (c) shown. It can be seen that the intensity of the SPP mode coupled by the incident light of p-polarization and s-polarization has different dependence on the structural parameters.

[0043] There is a sharp corner in the defective pinhole structure, as shown in Fig. 1(a), when the incident light is illuminated, charges tend to accumulate in these regions and form hot spots. For p-polarized incident light, there are three hot spots at t...

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Abstract

The invention discloses a surface plasmon polariton directional coupler independent of polarization and a control method thereof. Asymmetric defective pore structures are processed on ridge waveguide with sub-wavelength so that an SPP mode can be obtained through directional coupling by using p-polarization and s-polarization incident light; the ridge waveguide only supports single mode; the SPP mode under which light is transmitted along the ridge waveguide is obtained by directional coupling of p-polarization and s-polarization incident light due to influence of defects; Transmission of the SPP mode, which is obtained by coupling ofp-polarization and s-polarization incident light, can be along the same and the opposite directions by adjusting defective geometric parameters; the overall intensity of the coupled SPP mode can be modulated by fully utilizing s-polarization incident light under the situation of transmission along the same direction; and information of polarization coded incident light is preserved under the situation of transmission along the opposite direction so that the SPP mode coupling process is independent of polarization.

Description

technical field [0001] The invention relates to the field of nanophotonics, in particular to a polarization-independent surface plasmon directional coupler and a control method thereof. Background technique [0002] Surface plasmon polaritons (SPPs) are transverse magnetic TM electromagnetic wave modes bound at the metal-dielectric interface. Due to their excellent subwavelength field confinement and strong field enhancement effect, SPPs are considered as potential next-generation information carriers. Coupling free-space light into SPPs is crucial for studying the performance of plasmonic devices. This has led to a lot of research on SPP unidirectional coupling devices. Unidirectional coupling devices can efficiently couple free-space light into SPPs propagating in specified or interested directions on metal planar or ridge waveguide structures. However, due to the intrinsic polarization-dependent property of SPPs (TM polarization), only the incident light with p-polariz...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H01P5/18
Inventor 陈建军孙成伟容科秀李洪云龚旗煌
Owner PEKING UNIV
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