Controllable Precipitation Of Functional Crystals In Glass And Potential Application

The study on precipitation of functional crystals in glass has a long history. Now glass-ceramics are regarded as promising material for the applications in architecture, optical devices and artificial joint etc. With the development of information technology, micromation and integration of optical devices are becoming more and more important for the technique. One of the effective way to promote the micromation and integration of optical devices is to integrate the functional crystals in glass space-selectively. Conventional heat-treatment crystallization makes the crystals distribute in glass randomly, which is hard to achieve the space-selective controllable of crystallization region. Therefore, researchers try to investigate about controllable precipitation of functional crystals in glass in order to meet the demand of micromation and integration of optical devices.Femtosecond laser has the unique characteristics of space selectivity and ultrahigh peak intensity. High repetition rate femtosecond lasers have been widely used to induce crystallization within glasses due to their ability to rapidly and precisely deposit energy through nonlinear excitation and absorption. When a high repetition rate femtosecond laser is focused into glass, an increasing amount of energy will continuously accumulate in the modified region where a high temperature elevation occurs. When the local temperature reaches a certain temperature range for nucleation and crystal growth, crystals will be precipitated in the modified region.In this thesis, controllable precipitation of functional crystals in three glasses induced by high repetition rate femtosecond laser was investigated. We also investigated the crystals distribution and potential applications. The details are described as follows:1. Space-selective precipitation of deep-UV BaAlBO3F2 crystals inside a transparent glass induced by high repetition rate femtosecond laser pulses has been successfully achieved. The crystalline distribution in the modified region is examined by Raman spectra and Raman mapping. We also investigate the influence of laser average power and exposure time on the second-harmonic generation(SHG) intensity of BaAlBO3F2 crystals. The transmittance of the glass sample before and after the femtosecond laser irradiation is analyzed by absorption spectra. We investigate the possibility of the glass sample as deep-UV coherent light source for the application in 3D integrated optics.2. Space-selective precipitation of ZnO crystals inside silicate glass induced by high repetition rate femtosecond laser pulses has been achieved. Raman spectra and Raman mapping are used to confirm the existence of ZnO crystals and examine the crystalline distribution in the modified region. Electron Probe Micro-Analyzer(EPMA) and the simulation of temperature distribution were used to investigate the mechanism of crystals distribution. We also investigate the influence of laser average power on the precipitation of ZnO crystals. Based on the controllable luminescence of ZnO crystals in glass, we demonstrate the possibility of 3D optical data storage in the glass.3. We investigate the micro-structure and optical properties of Zn O-TeO2-P2O5(ZTP) glasses. Absorption and Raman spectra and high resolution transmission electron microscope(HRTEM) are used to analyze the origin of coloration and the network structure of the ZTP glasses. No metallic Te particles were observed in glass samples while ZnTe quantum dots appeared in these phosphotellurite glasses. We also investigate the third-order optical nonlinearities of these glasses embedded with Zn Te quantum dots by Z-scan technique. At the same time, controllable redistribution of precipitation of ZnTe nanocrystals in glass was induced by high repetition rate femtosecond laser irradiation. Raman spectra and Raman mapping are used to examine the crystalline redistribution in the modified region.Femtosecond laser induced space-selective precipitation of crystals in glass is promising for application in integrated optical devices.