Abstract
Abstract In common plasmonic configurations, energy loss and field enhancement are mutually restricted. In a vast majority of cases, high confinement goes together with high loss, which is a serious limitation for some applications. In an attempt of breaking this rule, which holds true for surface plasmon polariton (SPP) resonators, a multilayer trench grating microstructure with an asymmetric waveguide is considered. It supports both Fabry-Perot (FP) and cavity modes, whose hybridization exhibits unusual properties. The electric field enhancement was modulated by regulating the corresponding absorption and radiation quality factors. At the same time, energy loss was reduced, which is fundamentally ascribed to the mutual recycling of radiation energy between FP and cavity resonators. The maximum total quality factor and strongest field enhancement were both observed at the vicinity of quasi-static limit, thereby signifying that the structure exhibited simultaneous optimizations of field enhancement and loss inhibition, which is crucial to the design of high-quality SPP-based devices.
Highlights
In the area of high-quality plasmonic structure research, the reduction of energy loss without weakening the energy confinement is a crucial issue
The strong enhancement and the ultra-small mode volume of the electromagnetic field are among the main characteristics of some plasmonic structures, especially optical antennas [1,2,3], which bring into play a first class of potential applications to sensitive photodetection [4], surface-enhanced Raman spectroscopy [5, 6], nonlinear nanophotonics [7], infrared absorption enhancement [8,9,10], and display technologies [11, 12]
The above significant effects are obtained at the expense of additional effective mode volume of cavity mode, the proposed approach for improving the performance of widely used surface plasmon polariton (SPP)-based composite structures is effective, which is fundamentally distinguished from the Localized surface plasmon resonances (LSPRs)-based work of Seok et al, and worth taking this step forward
Summary
In the area of high-quality plasmonic structure research, the reduction of energy loss without weakening the energy confinement is a crucial issue. The configurations with low losses and high-quality factor (Q) values are strictly required in another class of applications to interferometer waveguides [13], ring resonators [14,15,16], and plasmon nanolasers [17,18,19,20]. The combination of the LSPRs with whispering gallery mode results in an extremely high Q factor within an optical microfiber [23]. Another line of thought to improve the structure’s quality is to associate LSPRs with the photonic states [24]. A detailed discussion on the underlying mechanisms is given below
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