利用半導體光放大器來穩定主動諧波鎖模光纖雷射之研究

Abstract

在本論文中我們同時從實驗及理論上研究了主動諧波鎖模光纖雷射及其加上半導體光放大器後之穩定效果。在實驗上我們利用極化分光器結合極化光纖迴路與非極化光纖分支構成一個對偏振態不敏感的雷射共振腔，再藉由半導體光放大器來穩定脈衝振幅的擾動，得到在重複率為2.5GHz及10GHz時，脈衝寬度分別為21.63ps、12.98ps之光脈衝序列，平均功率約為0.4mW，超模抑制率可穩定保持超過54dB以上。在理論上我們則是利用由變分法所求得之脈衝參數演化方程式來模擬此雷射系統，從模擬中能夠證實半導體光放大器確實對超模的抑制有其貢獻，並能得到穩定脈衝輸出的結果。

In the thesis we study an active harmonic mode-locked fiber laser stabilized by a semiconductor optical amplifier both experimentally and theoretically. In the experimental side, we construct a polarization insensitive fiber laser by using a polarization beam splitter to combine a PM-fiber loop with a Non-PM fiber Branch, and by placing a SOA in the cavity for stabilizing the pulse fluctuations. We obtain periodic pulse trains with 21.63ps and 12.98ps pulsewidth respectively at 2.5GHz and 10GHz repetition rates. The average output power is 0.4mW and the super-mode suppression ratio is above 54dB. In the theoretical side, we have simulated the fiber laser by solving the evolution equations of the pulse parameters derived from a variational method. From our simulation we confirm that the SOA indeed can suppress super-mode noises and help to produce stable laser pulse outputs.