The relation study between material structure and transmission efficiency on Cr4+:YAG crystal fiber by LHPG

• Main Authors: Hung-Jen Wang, 王弘仁
• Other Authors: Yen-Sheng Lin
• Format: Others
• Language: zh-TW
• Published: 2008
• Online Access: http://ndltd.ncl.edu.tw/handle/33464136818122671878

碩士 === 義守大學 === 電子工程學系碩士班 === 96 === For the generation of broadband tunability over 1.3 ?m to 1.6 ?m range in optical communications, Cr4+ ions have been demonstrated in a number of hosts including Cr4+:forsterite, Cr4+:Y2SiO5, and Cr4+:YAG. Since YAG is a cubic crystal with Ia-3d space group, its excellent thermal and optical properties has drawn extensive studies. However, a systematic study how the microstructure of Cr4+:YAG crystal fiber affects propagation loss is still lacking. In this study, the microstructure and optical characteristic were studied of Cr4+:YAG crystal fiber which was grown by the laser-heated pedestal growth (LHPG)method, and the drawing tower method was also mentioned for comparison. The LHPG method can easily change growth conditions, such as growth speed and CO2 laser power. A double cladding structure was developed, which have YAG composition as core, silica/YAG composition as inner cladding and silica composition as out cladding, respectively, the smallest core diameter we had grown was 11 ?m. In this thesis, the growth process of the Cr4+:YAG crystal fiber laser and optics coating design to enhance Cr4+ content were also involved. In addition, the composition of Cr4+:YAG crystal fiber was investigated by electron-probe micro-analyzer (EPMA) and energy dispersive X-ray spectrometer (EDX), which confirmed the relation between Cr4+ fluorescence effect and dopant concentration of CaO and Cr2O3. In order to understand the relation between the microstructure of Cr4+:YAG crystal fibers and the growth conditions, high-resolution transmission electron microscopy (HRTEM) was employed, which reveals the nano-scale information in the core and, inner-outer cladding interface, the inter-diffusion between core and inner cladding during growth process was also analyzed.