Microsphere-coupled three-dimensional tapered metallic waveguide structure and light field coupling simulation method

Abstract

The invention discloses a microsphere-coupled three-dimensional tapered metallic waveguide structure and a light field coupling simulation method. The structure includes three-dimensional aperture tapered metallic waveguide and a dielectric microsphere; the dielectric microsphere is arranged in the three-dimensional aperture tapered metallic waveguide and tangent to the inner wall of the three-dimensional aperture tapered metallic waveguide; and the taper angle of the three-dimensional aperture tapered metallic waveguide is greater than the critical taper angle which is required to meet a heatinsulation condition. An optical cavity can be constructed by embedding the dielectric microsphere into the inner wall of the three-dimensional aperture tapered metallic waveguide at a large taper angle (non-adiabatic condition) and a large incident port; and through the combination of waveguide structure optimization design, a high order transmission mode can be utilized to couple resonance excitation and effectively transmit compressed GSPs.

Description

technical field [0001] The invention relates to the field of optics, in particular to a three-dimensional tapered metal waveguide structure coupled with microspheres and an optical field coupling simulation method. Background technique [0002] Nanofocusing, that is, the efficient transfer and concentration of light energy to the nanoscale, has become an important topic in modern nanophotonics and nano-optics, and the conversion of light into surface plasmon polaritons (SPPs) is considered to be the key to achieve this goal. One of the most promising methods. Typical plasmonic nanofocusing is achieved with tapered waveguides. Such tapered waveguides can be divided into two categories: insulator-metal-insulator (IMI) structures, such as tapered metal rods, nanorods, metal film cones, and nanoedges for slow surface plasmon (SSP) nanofocusing; MIM structures, such as Conical field lines, conical gap, conical V-groove, used for nano-focusing of gap surface plasmons (GSPs:gap s...

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Problems solved by technology

[0007] 3. TMWG usually uses the "fire-end" method to directly use the lowest order transmission (TM 0 ) mode coupling to excite SPPs, in order to reduce metal absorption and reflection losses and improve the excitation efficiency of GSPs, the size of the incident port generally cannot be larger than one optical wavelength, thus increasing the coupling difficulty of the incident light field and limiting the increase of the power density of the light field;

[0008] 4. The transmission light field obtained at the aperture is derived from the lowest order transmission of the light field in ATMW (TM 0 ) mode cutoff and its evanescent field attenuate radiation, the coupling efficiency will decrease sharply with the decrease of aperture size

Therefore, the ATMW evanescent attenuation method can usually only obtain low-noise sub-wavelength transmission light field with low power density, which greatly limits the application of ATMW in ultra-high-resolution near-field imaging, ultra-high-density storage, nanolithography and Application promotion in research fields such as local nonlinearity

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