本論文主要研究目標為利用熱擴散纖核法改善模態場不匹配所導致能量大量損失，進而使穿透率大幅下滑的問題。文中所探討的模態場不匹配光纖為10/125-08 SCF與HI980，實驗中所使用的雷射源架構為全光纖式雷射，以改善傳統半導體雷射波長不穩定的問題，其中的增益介質為摻鐿光纖，雷射源後端會加入特殊的能量比例量測架構，來規避掉雷射源能量不穩定的問題。在尚未進行熱擴散纖核法改善前，本實驗架構之兩光纖穿透率大約落在50%左右。文中會先以傳統常見的光纖熔接機其內部追加放電加熱功能來進行熱擴散纖核實驗，也嘗試了反接式的追加放電加熱法，最終實驗結果兩者之平均最大穿透率可分別提升至83.00%與84.45%，且後者在實驗穩定度能獲得40%左右的提升。後續便嘗試以追加放電加熱法為基礎，加入氫氧火炬來達成混合式燒熔的手法，測試最佳結果為先經過4次Re-Arc及十分鐘的氫氧火炬燒熔後，最大穿透率能提升至97.60%，且平均只需約370秒便能達到90%以上的穿透率，但此手法也存在過長的Buffer time以及光纖容易因燒熔產生彎曲等問題，因此後續又分別加入高速以及慢速拉細兩種方式進行改良與比較。藉由高速拉細實驗得知拉細能良好的改善Buffer time的問題，使效率大幅提升，只需約177秒便能使穿透率達90%以上，但仍存在些微光纖彎曲的問題，而慢速拉細能使效率進一步提升，只需約160秒就能達到穿透率90%以上，且能完美解決光纖彎曲的問題。

This thesis studies on the thermally expanded core technology to improve the transmission loss due to the mode field mismatch. We use the all-fiber laser to be our laser source for the TEC experiment, which can make a more stable laser wavelength than the laser diode. Then we set a special measurement structure, which uses the proportion of the power to measure the result. By this way, this measurement structure can avoid the unstable power from the laser source. In the experiment, first, we use the Re-Arc by the fusion splicer to do the TEC experiment. That can improve the transmission from 50.66% to 83.00%. We also try Re-Arc by swapping fiber to do so. This way can make the transmission up to 84.45%, and make the result more stable then Re-Arc. Then we try TEC by mixed Re-Arc and H2-O2 Torch. By this method, we can make the transmission over 90% easily, and only need about 370 seconds to make transmission up to 90%. But we found that this way will make the fibers bended, and have a buffer time problem to make the efficiency pretty low. So we join the high-speed pulling to improve these questions. After the high-speed pulling, the buffer time problem can be solved successfully. We only need about 177 seconds to make transmission up to 90% by this way. But we found that still makes the fibers bended after the high-speed pulling. So we try the low-speed pulling to improve this problem. After the low-speed pulling, we only need about 160 seconds to make the transmission up to 90%, and the bending problem will perfectly solved by the low-speed pulling.

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