Investigation On The Filtering Characteristics Of Regulable Surface Plasmon Based On Electrowetting Technology

Surface plasmons have shown great application prospects in many fields due to their unique properties such as breaking through the diffraction limit and local field enhancement.However,due to the limitation of the structure fixing or adjusting method of the traditional plasmon components,it is difficult to meet the current requirements for precise and dynamic control of the light field.Therefore,it is very necessary to study the new technology of plasmon light field generation and dynamic regulation.Electrowetting technology is a technology that changes the wettability between conductive liquid and solid by applying voltage.The adjustment method using liquid as medium can effectively shorten the adjustment time,improve the adjustment efficiency,and enhance the flexibility.At the same time,the adjustment process is reversible and has strong stability,thus becoming a new method for the design and preparation of rapidly adjustable optical devices.This thesis innovatively proposes active plasmonic components based on electrowetting technology,and studies their filtering performance.By coating a hydrophobic dielectric layer and filling the liquid in the interspace of the metal micro-nano structure to form a fluid-controlled electrowetting device,the dielectric constant of the surrounding medium of the metal is changed during the adjustment process,and the properties of excited plasmon will also change accordingly.The main tasks of this thesis are as follows:(1)A tunable surface plasmon metal coupling structure filter based on electrowetting technology is designed.Two kinds of liquids with different polarities are added to the cavity in which the substrate is metal,and the distance between the particles suspended at the interface between the two liquids and the substrate is adjusted by the electrowetting technology.At the same time,the environmental medium around the particle is changed to realize the shift of the absorption peak in the visible range of the device.The results show that the device can reflect different colors of light,and the same structural unit can achieve selective absorption of the three primary colors.(2)A tunable surface plasmon grating filter based on electrowetting technology is designed.By coating a hydrophobic dielectric layer on one or both sides of the grating spine,a symmetrical or asymmetrical filter can be formed.By adding two liquids with different polarities into the space between the spines,the range of the dielectric constant of the environmental medium around the metal spine can be increased to form a grating filter with adjustable refractive index.The designed structure can dynamically adjust the hue and saturation of colors in the visible light range.(3)A plasmon waveguide filter based on electrowetting technology is designed.By adding two liquids with different polarities to the rectangular resonant cavity of the MIM waveguide structure,the voltage applied between the metal waveguide and the conductive liquid can change the effective refractive index in the resonant cavity.The filter effect of the waveguide structure was further studied by changing the resonator size,the coupling distance between the waveguide and the resonator,and the refractive index of the resonator.