雙纖衣摻鉻釔鋁石榴石晶體光纖之大自發輻射研究

Study of Cr4+:YAG Double-clad Fiber ASE

楊牧翰(Mu-Han Yang)

指導教授 ： 黃升龍

國立臺灣大學/電機資訊學院/光電工程學研究所/碩士(2009年)

https://doi.org/10.6342/NTU.2009.03060

摘要

光學同調斷層掃描術在具有高解析度，真時影像掃瞄和非侵入性等特生，未來在細胞等級的檢測具有很大的發展潛力。現在有很多寬頻光源應用於光學同調斷層掃描上，如superluminescent diode、鈦藍寶石鎖模雷射、 LED，熱鎢鹵素燈等等，這些光源的頻寬很寬，因此在光學同調斷層掃描上，有很高的縱向解析度。然而當考量到影像品質，光源的頻譜形狀就是一個重要因素。有些光源由於干涉訊號的side lobe影響，使得影像品質很差。此外為了得到高的訊雜比，一個方法是降低雜訊，另一個方法是提高光源功率。
本論文我們討論了製作雙纖衣摻鉻釔鋁石榴石作為光學同調掃描術的光源。我們製作雙纖衣摻鉻釔鋁石榴石頻寬有245 nm，縱向解析度達3.6 μm。為了提高訊雜比，我們利用雙向幫浦和在端面鍍放大自發輻射高反射膜，最佳化放大自發輻射功率，總輸出功率可達3.15 mW，此外，本論亦探討幫浦光極化時放大自發輻之影響。

同時我們亦投入了製作雙纖衣摻鈦藍寶石晶纖，目前我們可以成功生長出纖心尺寸48 μm的晶纖，放大自發輻射光的頻寬可達164 nm，以其用在光學同調斷層掃描，縱向解析度可達1.56 μm。

關鍵字

光學同調斷層掃瞄術 ； 雙纖衣摻鉻釔鋁石榴石晶纖 ； 寬頻光源 ； 摻鈦藍寶石 ； 晶體光纖 ； 雙向幫浦

並列摘要

Optical coherence tomography (OCT) will play an important role in the future due to the high resolution, real time imaging, and the noninvasive detection for human cell. There are many light sources beam applied to OCT such as superluminescent diode, mode-locked Ti:sapphire laser, LED, thermal tungsten halogen lamp, ect. Because of the broadband spectrum, all these sources have high axial resolution. Take image quality into account, the spectrum shape is an important factor. Some of these light sources suffer from poor image due to the side lobe of the point spread function. In addition, higher signal to noise ratio can support better image quality. To achieve higher signal to noise ratio, one way is to reduce the noise, and another way is to enhance the light source power.
In this thesis, we report the fabrication of Cr4+:YAG double cladding fiber as the broadband light source for OCT. The bandwidth of Cr4+:YAG double cladding fiber is about 245 nm, the axial resolution for OCT system is 3.6 μm. We also optimize the output of ASE by dual pump set and ASE HR coating on the endface of fiber, in order to enhance the signal to noise ratio. A total output power of 3.15 mW was achieved. In addition, in this thesis, we discuss the polarization effect of pump light on ASE.
We have also fabricated Ti:Sapphire double cladding fiber. So far, we can fabricate double cladding fiber with 48 μm core size. The bandwidth of ASE is 164 nm, which can be used for OCT with an axial resolution of 1.56 μm.

並列關鍵字

optical coherence tomography ； Cr4+:YAG double-clad fiber ； broadband light source ； Ti:sapphire ； crystal fiber ； dual pump

參考文獻

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