Research On Active Plasmonics And Applications Based On Metallic Micro/nano-structures

Localized surface plasmon resonance(LSPR)can be applied to biochemical sensing,data storage,thin-film solar cell and optical devices in nanoscale due to their special properties,such as surface localized effect and near-field enhancement.Based on the basic characteristics of LSPR,the quasi electrostatic approximation theory and the finite element method,this paper focuses on the control of the optical response of LSPR by gain doping and applied bias modulation.With these LSPR control methods,we propose a variety of metal nanostructure to realize the environmental refractive index sensing,LSPR amplification,molecular detection and other functions,and their performance is analyzed by simulation.The research contents of this paper are as follows:(1)Design an Au spherical nanoshell coated gain-assisted silica-core refractive index sensor.Using quasi-static approximation calculation,the simulated results show that a proper level of gain incorporated in the core layer strongly enhances the scattering efficiency as well as the quality factor of LSPR.Meanwhile,the sensors' figure of merit is enhanced 2000 times nearly compared to that without gain.(2)A low gain doped surface plasmon amplification is realized.Based on the concept of gain medium compensation for metal loss and the optimization of structural parameters of nanostructure,a low gain doped surface plasmon amplification is realized.Meanwhile,the physical mechanism of the lower gain threshold has been explained and discussed in detail by investigating the quality factor(QF)and the localized field distributions associated with the LSPR.(3)Desigen a new LSPR refractive index sensor,which bases on the bias-scanning.According to the relationships among the incident light and the applied voltage,the environmental refractive index,and the scattering spectra of metal nanoparticles,it is found that the bias-scanning can replaces the traditional wavelength scanning.The theoretical and simulated results confirm the uniqueness of the incident wavelength.Meanwhile,the sensitivity of the bias-scanning sensor can be further improved by adjusting the size and shape of metal nanoparticles.(4)A molecular sensor based on the active Fano-resonance has been realized.Combining the enhanced absorption effect of Fano-resonance with the characteristics of the bias-modulated conductivity of graphene,the active Fano-sensor is designed to realize the function of detection of low concentration and thin layer of bio-molecules.By adjusting the position of Fano-resonance,it can achieve the optimal overlap with the specific absorption bands of bio-molecules,thus greatly improving the infrared absorption signals of bio-molecules.