Design of an optofluidic sensor based on metamaterial absorbers for detection of organic materials.

In this paper, a dual-band ultra-narrow metamaterial absorber for sensing applications is presented. The unit cell of the structure consists of an Ag disk resonator located on a thin stack of graphene/SiO2/Au layers. The absorber shows high reflectivity in the whole of the incident light, ranging from 1.05 to 1.45 μm. Simulation results obtained by the finite-difference time-domain (FDTD) method indicate that the resonance behavior of the absorber depends on different factors including geometric parameters, the materials of the structure's components, the chemical potential of the graphene sheet as well as the shape of the resonators. For the optimal structure, the sensitivity, figure-of-merit (FOM) and quality-factor characteristics are as high as 760 nm/RIU, 109 RIU−1, and 193, respectively. Also, the absorption can reach 99.96% in the on-resonance wavelengths. As an optofluidic sensor, this structure can detect industrial analytes such as Methanol, Ethanol, Pentanol, Butanol, and Propanol with high accuracy. The proposed sensor has the advantages of high absorption, high sensitivity, and a fabrication-friendly structure, promising a great platform for the detection of industrial analytes. [ABSTRACT FROM AUTHOR]