中文摘要

近年來光電技術發展迅速，因而順勢推動半導體雷射幫浦固態雷射之發展。本研究目的是希望結合半導體雷射體積輕、薄、短、小及固態雷射高峰值功率與高品質輸出模態的優點，開發出轉換效率高、壽命長、結構簡單、散熱容易，但增益介質體積卻比原塊材少千分之一的晶體光纖雷射系統。

生長晶體的方法有許多種，本實驗室採用LHPG (laser heated pedestal growth) 法生長晶體光纖，此方法具生長速度快，控制容易及無坩堝污染等優點。目前可生長出23~365um之高品質Nd:YAG晶體光纖，並且發現在其橫截面上Nd離子濃度有內高外低的分布，進而使得光在此晶體光纖傳輸過程中有自聚焦的現象。使用直徑220um峰值濃度達1.6-atm.%的Nd:YAG晶體光纖，本實驗室已發表斜率效率達28.9%，輸出功率145mW的實驗結果 。

若適當的控制生長速度及縮徑比，可生長出直徑125um，外圍Nd濃度約0.8-atm%，峰值濃度達3.6-atm%的Nd:YAG晶體光纖，而濃度差所造成峰值與周圍折射率差平均值，從0.0036增加到0.0076。此折射率分佈對於光傳輸可產生集光效果，期望有助於降低晶體光纖內部的傳輸損耗，提升雷射斜率效率。

The rapid developments in optical and electronic technologies have accelerated developments of solid state laser technology. The diode-pumped solid state laser has the merits of the diode laser, such as compactness, low cost, and the merits of the solid state laser, such as high laser quality, high conversion efficiency, long lifetime, and simple structure. There use in laser applications is very cost-effective in terms of material consumption, which is typically one-thousandth that of bulk material. In addition, heat dissipation in the gain medium can be significantly alleviated because highly heat-conductive material can be applied to the circumference of the crystal fiber. So, it was applicated in electronics, communication and medicine widely.
The laser-heated pedestal growth (LHPG) method is now a well-established technique for the growth of single-crystal fibers. It is crucible free and can therefore produce high-purity, low-defect-density single crystals. Interface loss is one of the dominant factors that reduce the efficiency of crystal fiber lasers, although cladding with a dielectric coating or in-diffusion of the gain core has been utilized to suppress this interface loss. Using a gradient-index Nd:YAG crystal fiber with peak Nd concentration up to 1.6-atm.%, we recently demonstrated a laser power of 145 mW and slope efficiency 28.9%.
Peak Nd concentration up to 3.6-atm.% Nd:YAG crystal fiber with a 20-um core was grown, which could eliminate the interface loss and enhance the efficiency of crystal fiber lasers to be compatible with bulk solid-state lasers.

第一章 緒論 1
第二章 Nd:YAG晶體光纖雷射原理與元件製作 5
2.1 晶體特性 5
2.2 能階模型 8
2.3 傳輸模態 15
2.4 晶體生長方法 19
2.5 元件金相分析製程 24
第三章 Nd:YAG晶體光纖生長與量測 31
3.1電子微探儀之基本原理 31
3.2鍍碳技術 34
3.3生長參數與Nd濃度分佈之關係 36
3.4高濃度梯度晶體光纖 41
第四章 Nd:YAG晶體光纖雷射製作 43
4.1 光學鍍膜 43
4.2 晶纖雷射輸出特性量測 45
第五章 結論 50
參考資料 52
中英對照表 55

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