Broadband spps unidirectional exciter and control method based on asymmetric nano-groove structure

Abstract

The invention discloses a broadband SPPs unidirectional exciter based on an asymmetric nano-groove structure and a control method. The broadband surface plasmon unidirectional exciter of the present invention includes: a metal film; a main nano-groove is arranged on the surface of the metal film; an additional nano-groove is arranged on the bottom side of the main nano-groove to form an asymmetric nanometer Groove structure; by manipulating the relative amplitude and phase difference of SPPs excited by the depth regulation of the main nanogroove and the additional nanogroove in the structure, the unidirectional excitation of SPPs is realized, and further, the interaction between different modes in the nanogroove The interference effect becomes insensitive to the wavelength dependence, enabling the unidirectional exciter of broadband SPPs with a bandwidth up to 220 nm. The unidirectional exciter of SPPs of the present invention also has high performances such as high SPPs excitation efficiency and high extinction ratio, and an ultra-small size of several hundred nanometers, which is conducive to high integration, so it will be obtained in the ultra-high integration SPPs photon circuit widely used.

Description

technical field [0001] The invention relates to the field of nanophotonics, in particular to a broadband surface plasmon unidirectional exciter based on an asymmetric nano-groove structure and a control method thereof. Background technique [0002] Surface plasmon polaritons (Surface Plasmon Polaritons) 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 ...

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Problems solved by technology

However, since the unidirectional excitation of these SPPs is based on Bragg reflection or nearly complete coherence and destructiveness, there are strict requirements on the wavelength of the incident light, which is very unfavorable for realizing more complex multi-wavelength functional devices.

In addition, the strict requirements on the wavelength of the incident light also means that the sample processing is required to have high precision, which increases the difficulty of sample processing

By adding a dielectric film on the surface of the asymmetric nano-slit to increase the field confinement of SPPs, people have obtained a unidirectional exciter of broadband SPPs with a bandwidth of 100nm. However, the increase of the dielectric film not only shortens the transmission distance of SPPs, but also reduces It reduces the flexibility of device design and processing, which is not conducive to practical application

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