- 學位論文
晶體光纖側向濺鍍TiO2薄膜之製程與特性研究
The deposition and characteristic study of the TiO2 on crystal fibers
摘要
摻鉻釔鋁石榴石(Cr4+:YAG)晶體有許多應用，其所具有的3T2→3A2能階躍遷自發輻射光譜，包含了1.3 μm〜1.6 μm的寬頻特性，製成晶體光纖後，適合應用於光放大器、自發輻射放大光源及可調波長固態雷射、光學同調斷層掃描光源等領域，因此為非常實用之晶體材料。但其雙纖衣光纖為多模光纖，作為光源時，聚焦後進行影像訊息探測與掃描的相關應用上，會有空間解析度太低等問題須解決。 本實驗目的為均勻側鍍二氧化鈦(TiO2)薄膜於Cr4+:YAG晶纖側壁上，期望提升內纖衣(inner-cladding)折射係數，降低內纖衣與纖核心(core)折射係數差距，達到減少晶纖內可傳輸模態，提升應用於影像訊息探測時的空間解析度。同時探討二氧化鈦薄膜特性，利用通氧退火800℃使晶相轉變為高折射係數Rutile晶相，及側鍍於晶體光纖之影響。另亦對鈦薄膜經通氧退火，轉變為二氧化鈦薄膜後的結晶特性，以及側鍍鈦與二氧化鈦混合膜之效應做探討。利用晶相結構 (XRD)、薄膜微結構 (SEM)及薄膜光學特性 (SE)的量測，分析不同條件下所成長薄膜的基本特性。以及對應側鍍於晶體光纖後，內纖衣折射係數之變化。 在本研究中，利用反應式直流磁控濺鍍系統側鍍二氧化鈦薄膜至Cr4+:YAG晶纖，將內纖衣折射係數從1.65提升至1.72，但有其提升上限，二氧化鈦成分可能擴散、蒸發導致有其提升上限存在。
並列摘要
Cr4+:YAG has many applications, it’s 3T2→3A2 transition has a strong spontaneous emission from 1.3 μm to 1.6 μm. So it is suitable for optical amplifier applications, amplified spontaneous emission, wavelength tunable Solid State lasers and optical coherence tomography light source. It is a useful crystal material. But the double cladding fiber made by Cr4+:YAG crystal is a multi-mode fiber now. As a light source, in related application of scanning image information, the multi-mode fiber will induce lower spatial resolution. So we need to improve this property. To advance the spatial resolution of imaging application, we can decrease the difference of refractive index between fiber core and inner-cladding, by depositing TiO2 thin film on the side wall of cylindrical Cr4+:YAG fiber to increase refractive index in inner-cladding, then to produce a few modes or single mode fiber. In this research, we found the characteristics of TiO2 thin film about crystallinity, grain size and optical property measured by XRD, SEM and spectroscopic, and about Ti thin film transformation to TiO2 thin film by annealing with oxygen. We have deposited TiO2 thin films on Cr4+:YAG fiber by D.C. reactive magnetron sputtering system and successfully increase the refractive index of inner-cladding from 1.65 to 1.70. But it has a limit, the reason may be the diffusion or evaporation of TiO2 in fiber formation process.
參考文獻
延伸閱讀
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