研究光激發式半導體雷射在簡併與非簡併腔之空間與時間狀態

Abstract

本論文利用高功率的光激發式半導體雷射模組作為實驗的架構，雷射共振腔的組成由不同曲率平凹透鏡當作輸出鏡，改變激發功率與雷射共振腔長，觀察在簡併與非簡併腔之現象比較。在實驗過程中，利用在共振腔中架設光閘(Aperture)，探討高階橫模數量的多寡對於時域狀態的影響，發現當要產生完整的自鎖模現象時，不能單單只有縱模的存在，高階橫模的存在也是一大因素，接著觀察在簡併腔長底下，高階橫模頻率與縱模頻率為三分之一時，探討光激發式半導體雷射在簡併腔長下的空間與時域態表現，在實驗研究中透過改變不同曲率半徑的輸出鏡(ROC=100mm及200mm)及共振腔長，過程中發現雷射光斑呈現特殊的三角形圖案，在某幾個共振腔長中，有完整的自發性鎖模現象產生，我們也針對此現象去觀察與紀錄其變化行為。

We use high-power optically pumped semiconductor laser module as experimental architecture, the laser resonant cavity composed by the different curvatures plano-concave lens as an output mirror, via adjusting the pumping power and laser resonator length, observe transverse pattern, temporal trace and RF power spectrum in the non-degenerate and degenerate cavity. During the experiment, we add an aperture in the resonance cavity and investigate the influence of high-order transverse modes on the self-mode locking (SML) in an optically pumped semiconductor laser (OPSL). We discovered the temporal behavior becomes the random dynamics when too many high-order transverse modes are excited. In the degenerate cavity we found the laser spot that presents special triangular pattern when the ratio of fT and fL approaches to 1/3, we also found that the curve of output power will drop first and then rise.