Research On Metal Micro/nano Structure Design And Optical Properties Based On Surface Plasmon Interference

In recent years, with the development of integrated optics and micro-nano-technology, study about surface plasmonics has attracted wide attention. The particular characteristics of surface plasmon polaritons (SPPs), such as surface localization,shorter wavelength and extraordinary optical transmission offer a novel method to overcome the diffraction limit and accordingly attract significant attentions. Two different subwavelength metallic structures have been designed and the interference in them has been studied in this dissertation. The main research works and conclusions are as following:We report the design, simulation and characterization of novel plasmonic interferometric sensors that consist of semicircular grooves and apertures patterned on a gold film. This structure is proposed to form two-arm, three-beam, planar plasmonic interferometers. By combining the proposed plasmonic interferometers with a finite-difference time-domain numerical algorithm, we found that the transmission spectrum of the designed plasmonic structures can be readily tailored by changing arm lengths and number of grooves. Based on the principle, the characteristics of refractive index sensing are also demonstrated by simulation. Agreement between theory and simulation results demonstrates the operating principle of the device. These results show that this simple, efficient and controllable scheme possesses unique features of high contrast,narrow linewidth, and large amplitude.Apart from the structure above, a plasmonic Mach-Zehnder interferometric sensor based on a semicircular aperture-slit nanostructure patterned on a metal-insulator-metal film is proposed and demonstrated by finite difference time domain simulation method.Due to the interference between two different surface plasmon polariton modes in this design, the transmission spectra exhibit oscillation behaviors in a broad bandwidth, and can be readily tailored by changing SPP path length and core layer thickness. Based on this principle, the characteristics of refractive index sensing are also demonstrated by simulation. This structure is illuminated with a collimated light source from the back side to avoid impacts on the interference. Meanwhile, these results show that the proposed structure is promising for portable, efficient and sensitive biosensing applications.