Design Of Sub-wavelength Plasmonic Devices And Testing Methods

With the rapid development of information technology,photonic devices are becoming more and more important for the information transmission,processing and storage.However,due to the limitation of the optical diffraction limit,the size of traditional photonic devices can only be in the micrometer scale,which can not be matched with nanoscale electronic devices.Therefore sub-wavelength optical devices which can broke the optical diffraction limit have become a hot topic.When the size of photon device is reduced to the sub-wavelength order,a number of novel phenomena and characteristics will be exhibited.It has a significant difference with traditional photonic devices in the transmission mechanism of optical signal,the enhancement characteristics and optical force.Surface plasmons is one of the main research directions for sub-wavelength photonic devices.It can break through the optical diffraction limit and achieve the transmission and control of light under the sub-wavelength scale.Based on the novel optical properties of surface plasmons,novel sub-wavelength functional photonic devices have been proposed.These devices have shown great potential applications in many fields,such as all optical integrated chips,biochemical sensing,solar photovoltaic,surface enhanced spectroscopy and so on.The design and test research of components has important scientific significance and application value.In this thesis,we aimed to explore the propagation mechanism,design method of subwavelength plasmonic devices.It can be divided into two parts,devices based on surface plasmon polaritons and devices based on localized surface plasmons.On the one hand,the transmission characteristics of waveguides based on surface plasmon polarization are explored.On this basis,the optical transmission characteristics and structural optimization of resonant devices based on the waveguide were studied.On the other hand,the spectral characteristics,scattering enhancement and observing methods of metal micro/nano-structures based on locaized surface plasmon resonance were explored.Meanwhile,fabrication technology of subwavelength plasmonic devices was explored.The major achievements of the thesis are list as follows.Firstly,we systematically studied the polymer plasmonic waveguide and waveguide microring resonator.The mode propagation characteristics were studied by the numerical simulation model.The fabrication technology of the waveguide and the testing method were explored.In addition,the optical transmission characteristics,polarization characteristics and propagation losses were studied.On this basis,a microring resonator based on the waveguide structure was designed.The resonant characteristics of the resonator were analyzed with theoretical calculation,and the optimized structure of the resonator was obtained.Secondly,we designed an asymmetric structure of gold nanocrystalline based on the localized surface plasmons.Combined with three-dimensional finite element method,the optical properties,LSPR characteristics and Fano resonance characteristics of asymmetric nanocrystalline rings were studied.With the aid of plasmon hybridization model,the effective physical mechanism was explained.Lastly,we studied the observing method of nanoscale particles,and built the dark field microscopic imaging system.The system can real-time observe the behavior and imaging of metal nanoparticles with a size of more than 20 nm.On this basis,the spectroscopic testing method of nano particles was studied.The fabrication methods of gold nanotube arrays were studied and their LSPR characteristics were analyzed.The nanocolumn array showed good band-stop filtering characteristics,and also verified the feasibility of the dark field imaging system.The above research provided a feasible method for the microscopic characterization and testing of metal nanoparticles,and lays an experimental foundation for further research.