Characterization And Functionalization Of Micro-and Nano-structures Induced By Strong Field

In the21st century, the development of information technology, and the increasing demand for broadband network put forward higher requirement on the information communication technology. The integrated optical circuit, using photon or photoelectron as the information carrier, will replace the integrated electric circuit in future. The most important problem in the development of integrated optical technology is to fabricate various optical functional micro-and nano-structures in various materials, such as glass, with high precision and high efficiency. In recent years, researchers have found that using strong-field can induce functional micro-and nano-structures inside and on the surface of various materials, which have greatly promoted the development of integrated optical circuit.In this thesis, we studied the characterization and functionalization of micro-and nano-structures induced by strong fields. Two kinds of strong fields were used:high repetition rate femtosecond laser, and electron beam. Using these two kinds of strong field, we induced several kinds of micro-and nano-structures inside and on the surface of glass substrates. We studied the properties of these structures and their formation mechanisms. Furthermore, we demonstrated the applications of these structures in the relevant fields. A series of innovative results with practical significance and important conclusions were obtained.1. Using high repetition rate femtosecond laser, we induced the precipitation of copper nanoparticles inside glass substrate. The morphology, size distribution and space distribution of the copper nanoparticles were investigated. We studied the optical properties of the glass sample doped with cooper nanoparticles, and demonstrated its application in related field. Regarding the precipitation mechanism of the copper nanoparticles, we suggest that it is caused by the photo reduction due to various nonlinear effects during the femtosecond laser irradiation, as well as the diffusion and aggregation of copper atoms driven by the thermal field. We studied the precipitation position of the copper nanoparticles, and its dependence on the distribution of the femtosecond laser induced thermal field. We also observed the erasure of precipitated copper nanoparticles with the further femtosecond laser irradiation. Copper nanoparticles doped glass materials prepared with femtosecond laser irradiation can be applied in optical components, such as optical switches with ultrafast response rate, and3D colored laser glass internal engraving products. 2. Using high repetition rate femtosecond laser irradiation, we induced micro-protuberance structures on the surface of the glass sample, and micro-channel structure inside the glass sample. We studied the dependence of the morphology and size of the micro-protuberance structures on the femtosecond laser irradiation parameters and irradiation mode. As for the formation mechanism of the micro-protuberance structure, we suggest that it is due to the linear and nonlinear absorption of the femtosecond laser pulse energy by the glass substrate. Using the femtosecond laser direct writing technology, we induced the micro-channel structure inside glass sample. We used Rhodamine alcohol solution as the fluorescent substance, and characterized the size and connectivity of micro-channel structure. It is proved that the micro-channel structure have controllable length, uniform diameter, as well as good connectivity. The micro-protuberance structure can be applied in micro-lens and other optical components, while the micro-channel structure can be used in micro total analysis system.3. We studied the element redistribution behavior in the laser irradiated area of various glasses after high repetition rate femtosecond laser irradiation. In silicate glass, we observed the change in the relative content for glass network former ions and glass network modifier ions in the femtosecond laser irradiated region. The element redistribution mechanism was analyzed. We proposed that the diffusion of various glass component ions with different diffusion rates from the laser focal point to the surrounding area driven by the thermal field is the key point. We also observed the diffusion and aggregation of copper ions in the surrounding area where the temperature is below the glass melting temperature (Tm) for the first time to our knowledge. In tellurite glass, we observed an abnormal element redistribution behavior. In the femtosecond laser irradiated area, the relative content for different glass component ions remained unchanged, while the glass density changed significantly. We believe that the small structure units in the glass matrix, such as [TeO4] and [TeO3], play an important role in the formation of the abnormal element redistribution. Based on the femtosecond laser induced element redistribution, we can realize the spatial control of the micro-optical properties inside glass, which is very important for the preparation of optical components, such as optical waveguide.4. Using focused electron beam lithography method, we prepared gold nanostructures on glass substrate, and studied the size, morphology, surface plasmon resonance peak, and electric field distribution of the gold nanostructures. Using atomic layer deposition method, we deposited Al2O3films with different thickness on the gold nanostructures. The dependence of the peak position and peak intensity of the surface plasmon resonance peak on the thickness of Al2O3films was studied. We combined the Eosin Y molecules with the gold nanostructures and the Al2O3film, and carried out systematic study about the dependence of the enhancement of fluorescence intensity and fluorescence quantum yield on the thickness of Al2O3films. We found that in the case of1nm Al2O3film, the fluorescence enhancement effect is the best. We studied the mechanism for the fluorescence enhancement, and found that with the existence of metal nanostructures, the excited molecules can fall back to the ground state much faster by two means, the metal induced fluorescence quenching, and the surface plasmon induced increase in the radiative decay rate. The competition between these two pathways strongly depends on the thickness of space layer, Al2O3film. The surface plasmon induced fluorescence enhancement can be applied in the bio-and chemical sensing area. The fluorescence intensity of molecules with low quantum yield, such as DNA and protein substances, can be enhanced, resulted in the improvement of the sensitivity of fluorescence detection.