本篇論文為改善摻鐿光纖蝕刻到40微米後幫浦效率低落的問題。實驗以SMF130V取代摻鐿光纖進行蝕刻，經Rsoft模擬證明，只要光的模態數不超過135，蝕刻後的SMF130V就可以完美傳遞能量。因此蝕刻造成的缺陷是主要問題，我們利用氟素介面活性劑和40WCO2雷射退火兩種方法來改善蝕刻後SMF130V的穿透率。
氟素介面活性劑在光纖直徑蝕刻到51微米時可以提高穿透率，幅度約10~20%，在光纖蝕刻到40微米時反而使穿透率下降，原因在於介面活性劑和HF混合產生的沉澱物會影響蝕刻，而蝕刻時間長短會影響沉澱物多寡造成結果不同，所以此方法無法改善雷射幫浦效率。CO2雷射退火則可以達成目標，雷射的duty cycle調整為80，spot size 4mm，加熱時間200秒，掃描速度0.25mm⁄s，掃描距離10cm，最高可以提升穿透率達19.26%，未來可以應用在蝕刻摻鐿光纖上。

This thesis is to improve the problem of low pump efficiency when the Yb-doped fiber is etched to 40μm. The experiment used SMF130V instead of Yb-doped fiber for etching. By running Rsoft simulation, it proved that as long as the mode order of the light does not exceed 135, the etched SMF130V can perfectly transmit the energy. Therefore, the defects caused by the etching is the main problem. We use fluorinated surfactant and 40W CO2 laser annealing to improve the transmission of etched SMF130V.
Fluorinated surfactant can increase the transmission by 10~20% when the fiber diameter is etched to 51μm. The transmission is reduced when the fiber diameter is etched to 40μm because the precipitate produced by the mixture of surfactants and HF affected the etching. The etching time will affect the number of precipitate and cause different results. That is to say, this method cannot improve the pump efficiency. However, CO2laser can improve the transmission. We adjusted the duty cycle of the laser to 80, and set the heating time to 200sec, then set the scanning speed to 0.25mm⁄s, finally set the scanning distance to 10cm. With these parameters, we can increase the transmission by up to 19.26%. Therefore, the laser annealing can be applied to the etched Yb-doped fiber in the future.

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