| Since the Ebbesen research group observed the extraordinary optical transmission (EOT) phenomenon of light on metallic subwavelength periodic hole arrays in 1998, the surface plasmon polariton has received extensive attention from researchers at home and abroad. And a new subject called Plasmonics has been developed which focuses on the study of SPP and LSP (localized plasmon polariton). The study of SPP and LSP revealed a lot of novel phenomena and mechanisms in physics. It has many applications, such as collecting photons efficiently, polarization control and efficient absorption of light. It can also be used in many important optical devices, such as optical antenna, nanolaser and solar cells. Plasmon can enhance electromagnetic field significantly, which can be used in interaction with matter. The most common is the interaction with quantum emitter (QE). It can manipulate the spontaneous emission as well as control the fluorescence directivity of QE, so as to realize optical devices such as efficient single-photon source, single-photon switch and transistor. When interacting with two QEs simultaneously, it can generate two-qubit entanglement. It can be seen that the interaction between QE and metallic micro-nano structure has a very important physical meaning and a good application prospect. In this paper, we mainly study the special properties of the interaction between QE and different kinds of plasmons.We have studied the coupling of QE with metal-insulator-metal (MIM) structure. Firstly, we analyze the first magnetic resonance mode of MIM structure. Secondly, we study the enhancement of the spontaneous emission of QE, the Purcell factor, the ratio coupled into SPP-like (propagating magnetic resonance) mode, the β factor, and the sum of SPP-like, the η factor, namely the product of Purcell factor and β factor. By calculating these factors, we have studied the coupling effect of QE and MIM structure at first magnetic resonance and obtained a good coupling effect. Thirdly, we have optimized the coupling effect by changing the size of the structure. As the width of the structure increases and the thickness of the insulator decreases, the coupling effect will be improved when the magnetic resonance doesn’t change much. To achieve a good coupling effect at higher frequency, we have considered second magnetic resonance in MIM structure and obtained a good coupling effect. Thus, we have obtained a good coupling effect of QEs at different frequencies with nonradiative SPP-like mode.As the properties of nonradiative mode transformation of QE has been considered, we then consider the interaction of QE with plasmonic antenna, the radiation property of QE. The spontaneous emission of QEs, fluorescent molecules or quantum dots, is radiated along all directions, which severely limits the amount of collected light. It is very significant and remains a challenge to enhance the emission rate and control the fluorescence directivity. We introduce a cross plasmonic antenna (CPA) for the system of multiple quantum emitters with different emission wavelengths, where the excitation light scattering and emission fluorescence of different QEs are spatially separated in four different directions. The total enhancement factor of QEs can be up to more than one thousand times larger than that in vacuum. In addition, the fluorescence is strongly polarized. By adding a silver plate as substrate, the directivity can be further tuned in the whole upper half space. Our result shows that the CPA is promising for realization of an efficient, directional and strongly polarized nano-scale light source, which will have potential application in Nano-Optics. |
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