不同架構下之全保偏掺鉺光纖鎖模八字形雷射

Abstract

在這篇論文中，我們主要在研究全保偏光纖所構成八字型光纖雷射如何透過非線性放大迴圈鏡達到被動鎖模。為了達成低相位雜訊和穩定鎖模，我們測試許多不同元件和架構並且闡述腔內色散、非線性條件對雷射表現的影響。在每個架構中，我們量測了光功率、光譜和時域下的脈衝形狀等輸出特性並將不同架構下的量測結果互相比較。一些特別的結果像是：環圈間的切換行為、單孤子和束縛孤子也有被觀察到。除此之外，為了比較不同的鎖模機制，我也研究了透過非線性偏極旋轉的鎖模機制。最後，透過加入不可逆元件，我們成功做出可穩定鎖模，不受環境干擾的八字形雷射，它可以產生出次皮秒，彼此間距為20奈秒的脈衝，時序抖動為數個皮秒（積分範圍為1 kHz-1 MHz）的雷射，使其適合用於當作光纖光頻率梳的光源。

In this thesis, we demonstrate several ways of achievement of mode-locking in a figure-eight (F8) fiber laser which is comprised of an all polarization-maintaining (PM) fiber structure utilizing a nonlinear amplifying loop mirror to get passive mode-locking. In order to achieve stable mode-locking with low phase noise, different elements and configurations were tested and the influence of cavity dispersion and nonlinearity to the performance of laser were elucidated. For each configuration, output characteristics including output power, optical spectrum, and autocorrelation trace were measured and compared with precedent results. We observed a particular switching behavior and the single and bound solitonic characteristics. In addition, the mode-locking of non-PM fiber laser based on nonlinear polarization rotation (NPR) has been examined to compare with that of F8 laser based on nonlinear amplifying loop mirror. Finally, a stable mode-locked figure-eight laser with nonreciprocal elements is realized, which is immune to environmental fluctuations and delivers subpicosecond pulses separated by 20 ns with timing jitter of about several picosecond integrated from 1 kHz to 1 MHz. This high stability and environment-free performance of our laser is suitable to be further developed as a source of fiber optical frequency combs.