Ultra-narrow Band Perfect Absorber and Its Application as Plasmonic Sensor in the Visible Region

Abstract

We propose and numerically investigate a perfect ultra-narrowband absorber with an absorption bandwidth of only 1.82 nm and an absorption efficiency exceeding 95% in the visible region. We demonstrate that the perfect ultra-narrowband absorption is ascribed to the coupling effect induced by localized surface plasmon resonance. The influence of structural dimensions on the optical performance is also investigated, and the optimal structure is obtained with the extremely low reflectivity (0.001) of the resonance dip. The perfect absorber can be operated as a refractive index sensor with a sensitivity of around 425 nm/RIU and the figure of merit (FOM) reaching 233.5, which greatly improves the accuracy of the plasmonic sensors in visible region. Moreover, the corresponding figure of merit (FOM*) for this sensor is also calculated to describe the performance of the intensity change detection at a fixed frequency, which can be up to 1.4 × 105. Due to the high sensing performance, the metamaterial structure has great potential in the biological binding, integrated photodetectors, chemical applications and so on.

Plasmonic Sensors Based on Funneling Light Through Nanophotonic Structures

“…To improve sensitivity and FOM, the incoming light has to couple efficiently to surface plasmon resonances (SPR) with the narrowest possible lineshape at the desired wavelength range. A wide variety of designs have been proposed to produce these features [15,[21][22][23].…”

Design and realization of light absorbers using plasmonic nanoparticles

“…2, devices are generally highly polarization dependent and the absorption band is narrow, which makes them promising candidates for sensing applications, colored-optical filters [10] (see Fig. 3) and polarization detectors [11].…”

Narrowband Light Reflection Resonances from Waveguide Modes for High-Quality Sensors

“…As a result, only TE waveguide modes can be utilized for such a sharp Fano resonance to appear. Recently, perfect absorbers of electromagnetic waves have also been proposed theoretically and demonstrated for the sensitivity-enhancement of refractive-index sensors [ 31 , 32 , 33 , 34 , 35 , 36 , 37 , 38 , 39 , 40 , 41 , 42 , 43 , 44 , 45 , 46 ]. The most significant advantage of this kind of refractive-index sensor is that it allows the detection of a refractive index change by an almost dark reference measurement, even if only a few photons are reflected from the perfect absorbers of electromagnetic waves [ 32 ].…”