此論文使用全光纖系統，並利用cladding-pump的技術，以915-nm多模雷射二極體作為泵浦光源來激發摻鐿光纖，產生CW 976-nm雷射。但經模擬發現在cladding-pump系統下，泵浦強度過低，無法產生976-nm之雷射。故本論文主要目的是利用氫氟酸蝕刻縮減摻鐿光纖直徑，提升泵浦光源的強度，進而降低雷射門檻，使976-nm之雷射率先產生，且最佳化幫浦效率，進而提升雷射效率。我們發現用濃度為24.5%之HF蝕刻之光纖穿透率皆可保持在75%以上；反之，用30%之HF蝕刻之光纖穿透率皆低於20%，推測是用30%之HF去蝕刻光纖所製作之taper的斜率較大，使得多數的光折射出光纖外，故我們利用可精準調控轉速的馬達(PIA25)，製作不同taper長度之光纖並作比較，證實了taper斜率越緩和，穿透率越高。再者因為增益光纖的材質為磷酸鹽玻璃，故與一般光纖之蝕刻速率有所差異。根據這個結果我們將taper製作的位置從原本的DCF 20/125移至摻鐿光纖上，原本的作法會蝕刻到DCF 20/125與摻鐿光纖，所以會造成兩光纖臨界處半徑有落差，造成穿透率不佳，故將taper改變至摻鐿光纖上，便可改善此問題。在未經任何熱擴張纖核(TEC)處理模態場不匹配之損耗的條件下，我們將雷射效率從原本的51 mW/W(5.1%)，提升至82 mW/W(8.2%)；雷射門檻由2.9W降至1.9W；最大光功率由223.8W提升至320.5W，顯示確實有大幅改善雷射腔之泵浦效率。最後我們換上模態場直徑與共振腔較匹配之FBG，改善雷射架構中存在的模態場不匹配之損耗，證實能提升雷射效率。

This thesis studies on the cladding-pump technique to pump the ytterbium-doped fiber with a 915-nm multimode laser diode as a pumping source to generate 976-nm laser which is under the all-fiber system. We found that the Yb-doped fiber is difficult to laser at 976-nm in the cladding-pump system. Therefore, our main purpose is that etching the Yb-doped fiber by HF to decrease the diameter so that increasing the intensity of pump source and reducing the laser threshold. After that, we improved the quality of etching and optimized the pump efficiency to increase the laser efficiency. We found that the transmission of the SMF-130V etching by HF 24.5% was above 75%. The transmission of the SMF-130V etching by HF 30% is less than 20%, Presumably the slope of taper etching by HF 30% is larger, so that most of the light refract out of the fiber. We make different lengths of taper and compare their transmissions. We confirm that the smoother the taper’s slope become, the higher the transmission is. Next, the material of gain fiber is the phosphate glass, so that the etching rate between the Yb-doped fiber and SMF-130V is different. According to this result, we change the position of the taper from DCF 20/125 to Yb-doped fiber. Because of the different etching rate, the original etching method would result in the difference in diameter at the connection point of two fibers. It leads to low transmission. Changing the position of the taper can solve this problem. In the condition without TEC to reduce the loss of mode-field mismatch, we successfully increased the laser efficiency from the original 5.1% to 8.2%, the threshold decreased from 2.9W to 1.9W, and the maximum measured power from 223.8W to 320.5W.

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