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標題: | 摻鉻釔鋁石榴石晶體光纖寬頻可調波長雷射研究 The study of broadly tunable Cr4+:YAG crystal fiber laser |
作者: | Yi-Hsun Li 李奕勳 |
指導教授: | 黃升龍(Sheng-Lung Huang) |
關鍵字: | 寬頻光源,摻鉻釔鋁石榴石,晶體光纖,可調波長雷射,雷射加熱基座長晶法, Broadband light source,Cr4+:YAG,crystal fiber,tunable laser,laser-heated pedestal grown method, |
出版年 : | 2020 |
學位: | 碩士 |
摘要: | 摻鉻釔鋁石榴石(Cr4+:YAG)晶體適合應用於有寬頻光源需求的技術上,包含:光學同調斷層掃描術以及光通訊,Cr4+:YAG的寬頻頻譜位於近紅外波段的1.1 – 1.7 μm區間,其3 dB頻寬約270 nm,不僅涵蓋整個光通訊波段,在光學同調斷層掃描術的應用上也有優異的縱向解析度及較大的組織穿透深度。 本論文中的增益介質為摻鉻釔鋁石榴石晶體光纖,該晶體光纖先利用雷射加熱基座長晶法生長單晶纖心,再用共提拉雷射加熱基座長晶法以石英玻璃包覆纖心,形成纖心直徑僅有16 μm的低傳輸損耗雙纖衣晶體光纖,最後以電子束蒸鍍系統在晶體光纖端面蒸鍍介電質光學膜層作為雷射腔體中的增益元件。光纖結構提供優異的散熱效果並有效地降低雷射閥值,可以大幅提高此材料的實用性。 以高反射鏡為輸出耦合鏡的外腔式架構下,達成低閥值的Cr4+:YAG晶體光纖雷射,其雷射閥值和斜線效率分別為51 mW與10.7 %,並以不同偏振方向幫浦的雷射閥值推算出訊號光的激發態吸收對雷射的影響。本研究中也成功架設由光柵調變之低閥值且寬頻的可調波長雷射,其雷射閥值僅85 mW,該值低於文獻中的成果一個數量級以上,而波長可調範圍達170 nm,中心波長為1438 nm,範圍橫跨1353至1523 nm。由可調範圍中各波長的雷射閥值觀察到和波長相關的訊號光激發態吸收所造成的影響,也同時觀察到腔內訊號光強度增加使得激發態吸收效應更加明顯而導致雷射斜線效率降低的現象。 Cr4+:YAG is suitable for some applications such as optical coherence tomography (OCT) and high-capacity optical communication, which need broadband light source. The emission band is from 1.1 to 1.7 μm at near infrared region, and the 3-dB bandwidth is up to 270 nm. It covers all bands for optical communication, and it can supply better axial resolution and deeper penetration depth in OCT application In this thesis, the gain media was Cr4+:YAG crystal fiber. The core was grown by the laser-heated pedestal grown (LHPG) method. Then, the core was cladded with fused-silica by the co-drawing LHPG method. The low loss double-clad crystal fiber (DCCF) with 16-μm core diameter was fabricated. Finally, the both ends of DCCF were deposited with optical dielectric films by an electron beam evaporator. Benefit from the fiber structure, the heat dissipation became better and the laser threshold power became lower. External-cavity Cr4+:YAG DCCF laser with high reflection mirror as the output coupler has been demonstrated with a 51-mW threshold pump power and a 10.7 % slope efficiency. The impact of signal light excited state absorption (ESA) can be analyzed from the threshold pump power in different polarization pump. A broadly low-threshold grating-based Cr4+:YAG DCCF tunable laser has been successfully demonstrated with 170-nm tuning range centered at 1438 nm, from 1353 to 1523 nm. The threshold pump power was 85 mW, which was more than one order less than those in literatures. It was observed that the wavelength dependence and intensity dependence signal light ESA effect from the threshold pump power and the slope efficiency at different wavelength in the tuning range. |
URI: | http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/55172 |
DOI: | 10.6342/NTU202002135 |
全文授權: | 有償授權 |
顯示於系所單位: | 光電工程學研究所 |
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