以溶液法製備石墨烯飽和吸收體之被動鎖模光纖雷射

Abstract

在本論文中，我們利用溶液法成長兩小時下得到高品質的石墨烯薄片。再將此石墨烯薄片加工成石墨烯/聚乙烯醇合成物以及光纖端面直接轉鍍石墨烯薄膜兩種形式的飽和吸收體。利用這兩種形式的飽和吸收體置於摻鉺光纖雷射中，我們成功地產生被動鎖膜的短脈衝。 其中，石墨烯/聚乙烯醇飽和吸收體無法承受高功率的泵浦光來產生被動鎖膜。我們推測其原因為熱效應導致聚乙烯醇的穿透率下降以致脫鎖模。而直接轉鍍在光纖端面的石墨烯薄膜飽和吸收體不僅可以產生穩定的被動鎖膜，還可以承受超過350毫瓦的泵浦光。最後，我們成功地利用石墨烯薄膜飽和吸收體產生被動鎖膜的摻鉺光纖雷射擁有1557奈米中心波長的最大輸出光功率為15.4 毫瓦以及脈寬823.5 飛秒。

In this thesis, we obtained high-quality graphene flakes produced by liquid-phase exfoliation method under 2 hours ultrasonic time to fabricate graphene/PVA composite and directly coated graphene-film on fiber end as saturable absorbers for passively mode-locking Er-doped fiber lasers. We found graphene/PVA saturable absorbers cannot sustain high pumping power owing to the heat accumulation in PVA results in increasing intra cavity loss to cause unlock of the laser. On the other hand, graphene-film on fiber end can sustain much higher pumping power over 350 mW. Finally, we demonstrated passively mode-locked ultrafast Er-doped fiber laser with a maximal output power of 15.4 mW at central wavelength of 1557 nm and pulse duration of 823.5 fs using graphene-film as a saturable absorber.