環境穩定主動諧波鎖模摻鉺光纖雷射之研製

Abstract

在本論文中我們利用PM Fiber Loop與Farady Rotaing Mirror + Non-PM EDFA光纖放大器的架構來構成一個對偏振態不敏感(insensitive)的共振腔，並以此來製作具環境穩定效果的光纖鎖模雷射。我們先對主動鎖模以及利用鎖相迴路結合自相位調變和頻譜濾波器來穩定鎖模雷射輸出的原理作了理論性的介紹與分析，然後敘述我們的實驗結果。在實驗上，我們可以得到重複頻率為1.1 GHz之穩定時序脈衝序列輸出，此脈衝之寬度為32.5 ps、平均輸出功率約0.37mW，旁模抑制比(side-mode suppression ratio)最佳時可達60 dB以上，平均輸出功率之混亂度在5%以內。我們觀察到輸出脈衝序列之振幅及寬度仍有不小的變化，表示穩定機制的作用未如預期的好，我們也對此提出幾個可能的原因來做說明。

In the thesis we construct an environmentally stable active mode- locked Er-fiber laser by using a polarization insensitive cavity with a configuration composed of a PM Fiber Loop, a Faraday Rotating Mirror and a Non-PM Er-Doped Fiber Amplifier. The theory of active mode- locking as well as the principle of using a Phase-Lock-Loop, the SPM effect and a spectral filter for laser stabilization are analyzed and our experiment results are also described. Experimentally we obtain a time domain pulse train with 1.1 GHz repetition rate, 32.5 ps pulsewidth and 0.37 mW average output power. The best super-mode suppression ratio could be over 60 dB and the fluctuations of the average output power are below 5%. We have observed that the amplitude and pulsewidth of the output pulse train still fluctuate in time, which indicates that the stabilized mechanism is not as good as our expectation. Some possible reasons are proposed to explain the observed results.