Abstract
We propose and investigate a wide-angle and high-efficiency absorber by using the void plasmon (VP) effect in a Fabry–Perot (FP)-like system, which consists of a perforated metal film and a ground metal plane separated by a dielectric spacer. A hybrid FP/VP resonance mode contributes to the high absorption efficiency. Besides the increased absorption, greatly enhanced localized electric-field intensity at “hot spots” (~ 2284 times) can be achieved. In addition, by varying the thickness of the perforated metal layer and the environmental refractive index, the position of resonance peak can be easily controlled. The proposed absorber can also work as a sensor for detecting the surrounding dielectric constant with the maximum value of the figure of merit (FOM) achieving 3.16 in theory. This work creates an alternative design for high-efficiency absorption devices.
Highlights
Surface plasmon resonance (SPR), which is the coherent oscillations of electrons at the interfaces of noble metals and dielectric materials, is able to enhance the light absorption efficiency of noble metals [1]
To know the dispersion of the Void plasmons (VPs) effect and strengthen our previous interpretation, we examine numerically the angle-dependent dispersion of the VP mode
By the VP effect, high absorption efficiency up to 99.8% and strongly boosted electric-field intensity can be achieved at the resonance wavelength
Summary
Surface plasmon resonance (SPR), which is the coherent oscillations of electrons at the interfaces of noble metals and dielectric materials, is able to enhance the light absorption efficiency of noble metals [1]. The SPR-based absorbers have been widely researched with various plasmonic systems, including arrays of gratings [2–9], metallic nanoparticles [10–21], and nanoholes in metal films [22–25]. By changing the geometrical and physical parameters such as the shape, size, and material of structures as well as the dielectric environment, the absorption properties in the visible region can be effectively controlled and improved. Metallic nanoparticles are usually in company with the LSPs effect, while the perforations on the metallic film can induce both the PSPs effect and the void plasmon (VP) effect.
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