Abstract
The spontaneous-emission enhancement effect of a single metallic rectangular-aperture optical nanoantenna on a SiO2 substrate was investigated theoretically. By considering the excitation and multiple scattering of surface plasmon polaritons (SPPs) in the aperture, an intuitive and comprehensive SPP model was established. The model can comprehensively predict the total spontaneous emission rate, the radiative emission rate and the angular distribution of the far-field emission of a point source in the aperture. Two phase-matching conditions are derived from the model for predicting the resonance and show that the spontaneous-emission enhancement by the antenna comes from the Fabry–Perot resonance of the SPP in the aperture. In addition, when scanning the position of the point source and the aperture length, the SPP model does not need to repeatedly solve the Maxwell’s equations, which shows a superior computational efficiency compared to the full-wave numerical method.
Highlights
In the field of life sciences, particle-type optical nanoantennas [1,2,3,4] and aperturetype optical nanoantennas [5,6,7,8,9,10] can achieve single-molecule fluorescence detection even under high concentrations in physiological environments [9,10,11]
We investigate the fundamental resonant rectangular-aperture nanoantenna, and establish an surface plasmons polaritons (SPPs) model by considering the excitation and multiple scattering of the SPP in the aperture in order to clarify the role of the SPP in the spontaneous emission enhancement by the antenna
To explain the numerical results and clarify the underlying physics of the spontaneous emission enhancement of the rectangular-aperture nanoantenna, an intuitive semianalytical SPP model was built based on an intuitive excitation and multiple-scattering process of the SPPs
Summary
In the field of life sciences, particle-type optical nanoantennas [1,2,3,4] and aperturetype optical nanoantennas [5,6,7,8,9,10] can achieve single-molecule fluorescence detection even under high concentrations in physiological environments [9,10,11]. Compared with non-resonant aperture nanoantennas, resonant aperture nanoantennas can achieve a stronger fluorescence-excitation electric field and a higher spontaneous emission rate [6,19,20,21,22,23,25,26,27,28,29,30,31]. A rectangularaperture nanoantenna is one of the most basic structures It can be of great theoretical significance to investigate the mechanism of the resonance and its resultant spontaneous emission enhancement for the rectangular-aperture nanoantenna
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