Broadband SPPs one-way exciter based on asymmetric nanoscale groove structure and control method

Abstract

The invention discloses a broadband SPPs one-way exciter based on an asymmetric nanoscale groove structure and a control method. The broadband surface plasmon polaritons (SPPs) one-way exciter comprises a metal film, a main nanoscale groove is formed in the surface of the metal film, and an auxiliary nanoscale groove is formed in one side of the bottom of the main nanoscale groove to form the asymmetric nanoscale groove structure; the relative amplitude and phase difference of excited SPPs are regulated and controlled by controlling the depth of the main nanoscale groove and the depth of the auxiliary nanoscale groove, so that one-way excitation of the SPPs is achieved; furthermore, the interference effect among different modes inside the nanoscale grooves does not sensitively depend on wavelengths, and therefore bandwidth SPPs one-way exciter with the bandwidth reaching 220 nm is obtained. The SPPs one-way exciter has the high SPPs excitation efficiency, the high extinction ratio and other high performances, and has the super-small size of a few hundreds of nanometers, high integration is facilitated, and therefore the broadband SPPs one-way exciter is widely applied in an SPPs photonic circuit of the ultra-high integration level.

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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