Analysis On Surface Enhanced Infrared Absorption Characteristics of Multi-Resonance Optical Antenna

Abstract

Infrared spectroscopy is an important detection technique. Because each functional group of different molecules has a fixed vibration mode, the molecules can be detected by infrared spectroscopy in the mid-infrared region. Metal nano-optical antennas can be used to construct high-sensitive sensors to detect different molecules. A structure with multi-band plasmon resonance is designed, which is composed of one gold nanorod and two symmetrical opening frames in order to detect the different target molecules simultaneously. In this study, the surface electric field distribution of the optical antennas is simulated by using finite difference time domain method (FDTD). In addition, the effects of the optical antenna structure on the surface enhanced infrared absorption (SEIRA) characteristics of the antenna are investigated. The different modes can be coupled, which brings new plasmon resonance peaks. It has been analyzed by the localized surface plasmons theory. These results provide a theoretical reference for the application of the new infrared sensing technology and shed light on guiding further exploration of infrared detectors.