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Title: | 雙鏡式摻鐿釔鋁石榴石晶體光纖環形雷射之研究 Study of Two-Mirror Yb3+:YAG Crystal Fiber Ring Laser |
Authors: | Yen-Lo Huang 黃彥羅 |
Advisor: | 黃升龍(Sheng-Lung Huang) |
Keyword: | 雙鏡式環形共振腔,環形雷射,Yb:YAG,晶體光纖,分光鏡, Two-mirror ring cavity,ring laser,Yb:YAG,crystal fiber,beam splitter, |
Publication Year : | 2007 |
Degree: | 碩士 |
Abstract: | Yb3+:YAG 的能階結構簡單,少了如受激態吸收、concentration quenching…等寄生效應;其量子缺陷亦低,可以有效利用激發光;然而,準三能階的Yb3+:YAG雷射,其熱問題將嚴重影響雷射的輸出效率。
為了改善熱效應對增益介質Yb3+:YAG 的影響,我們使用生長快速、無坩鍋汙染問題的雷射加熱基座生長法將1.5×1.5 mm2 的Yb3+:YAG 方棒,生長成250 μm直徑的晶體光纖,提高增益介質的表面積對體積比來改善散熱,進而提升雷射效率。 以Ti3+:sapphire 雷射做為激發光源,使用直徑250 μm、1.33 mm 長的Yb3+:YAG晶體光纖做為增益介質,在雙鏡式環形共振腔的實驗架構中,經實驗証實,能將激發功率閥值降低至497.1 mW,相較於534 μm 直徑Yb3+:YAG 晶纖的589.9 mW激發閥值減少了約92 mW,表示提高散熱面積的確能降低熱損耗。 過去,我們必須更換不同反射率之耦合透鏡,並且重新調整雷射,以求得雷射輸出的最佳值,而且雙鏡式共振腔亦有多點雷射輸出、不易收集的缺點,於是我們利用高反射鏡作為共振腔,並在腔內加入分光鏡,讓雷射由分光鏡輸出,實驗上,由耦合透鏡的漏光只為由分光鏡雷射輸出的3%,其激發閥值約為584 mW。 Due to its simple energy level structure, there are no excited state absorption, concentration quenching, and etc. in Yb3+:YAG. Also, it has the potential for higher efficiency with its 8.6% low quantum defect. However, the quasi-three-level nature of Yb3+:YAG makes it more sensitive to increased temperature. In order to increase surface-to-volume ratio and relieve the thermal problem, we applied a 1.33-mm-long and 250-μm-diameter Yb3+:YAG crystal fiber as the gain medium, which was grown with our own LHPG system, in the multi-pass ring cavity instead of bulk, 1.5×1.5 mm2 Yb3+:YAG. The achieved threshold was 497.1 mW, which was about 92 mW lower than that using 534-μm-diameter fiber. In the past, the optimization procedure of the laser performance was tedious because when replacing mirror of different reflectance the laser cavity must be tuned again. And, the multiple laser outputs were not collected easily. In our new design, we use mirrors of high reflectance for the ring cavity and one beam splitter for dumping laser output. The leakage power for the cavity mirrors was only 3% of the power from the beam splitter and threshold was 584 mW. |
URI: | http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/29695 |
Fulltext Rights: | 有償授權 |
Appears in Collections: | 光電工程學研究所 |
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ntu-96-1.pdf Restricted Access | 8.85 MB | Adobe PDF |
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