使用波長掃描式脈衝光源之新型群速度色散量測技術

Abstract

群速度色散係數在高速通訊、非線性光學及超快光學等很多科學與應用研究上扮演著重要的角色，本論文提出一種新型色散量測的方法及架構，只需使用射頻頻譜分析儀來觀測週期性光頻率掃描的時域脈衝頻譜即可求得群速度色散值。論文中所使用的光源為非同步鎖模光固子光纖雷射，此乃實驗室先前發展的架構，並有著令人感興趣的特性，例如：脈衝的時間位置與中心頻率具慢速週期性變化等。此外，我們也提出以頻率調制器與振幅調制器所架設的光源來產生中心頻率週期性變化的脈衝光源的新想法。將此類具慢速週期變化特性的光源之輸出光脈衝序列通過待測光纖，藉由直接分析通過待測光纖前後的光脈衝序列之射頻頻譜圖來獲得脈衝時間位置慢速週期性變化的大小，即能以理論計算出待量測之群速度色散係數大小。

Group velocity dispersion (GVD) plays an important role in many applications such as high speed communication, nonlinear optics, ultrafast optical processing and other scientific researches. A new Group velocity dispersion (GVD) measurement method has been reported and demonstrated by using a periodic wavelength-scanning pulse source such as an asynchronously modelocked Er-fiber soliton laser or a frequency-shift keying (FSK) modulation light source with a RF spectrum analyzer. In the experimental work of the thesis, an asynchronous mode-locked fiber soliton laser has been used as the main light source. The laser was previously developed in our lab and is with some interesting properties including the slow periodic variation of the pulse timing position variation and the pulse central wavelength. By observing the pulse timing position variation of the pulse train before and after test fiber with the use of a RF spectrum analyzer, the group velocity dispersion of the test fiber can be inferred from the theoretical formula.