飽和吸收染料液滴雷射的共振腔量子電動力學穩態光譜研究

Abstract

我們建立了一套微米大小之具飽和吸收的染料微滴雷射系統來觀察其穩態 性質,根據共振腔量子電動力學的理論,該系統內由於共振模密度增大及模 間距的增加,自發輻射有增強的效應。而計算機模擬的結果顯示,自發輻射 速率越大者,其激升臨界值越低,在一個封閉的雷射腔中,激升臨界值甚至 完全消失。實驗結果也顯示激升採 霋P輻射強度為正比的關係且無激升臨 界值。另外,由於染料的低飽和吸收強度特性及其吸收截面與輻射截面重 疊的影響,此染料微滴雷射的共振光譜結構會隨染料濃度的增高而往長波 長偏移,且共振頻譜的譜寬分佈甚廣,並且在低染料濃度時,光譜譜線中出 現其它共振模階的譜線結構,我們將理論模型的預測與實驗的結果做比對, 得到與結果甚為吻合的解釋。 We build up a micrometer diameter size saturable absorbing liquid droplet dye lasers in order to observe it' s steady-state properties. According to cavity-QED, the laser system has enhancement of spontaneous emission when the oscillation mode density and the mode distance increase. The simmulated results show that the larger spontaneous emission rate, the lower excitation threshold, which even completely disappear in a closed laser cavity. Experimental result also identify the linear proportion relation of the excitation and radition intensity, and the nearly disappearing excitation threshold. On the other hand,the structure of oscillationspectra of microdroplet dye lasers have the red shift when the concentration of dye increase, because of saturation absorption characteristics and the overlap between absorption and radiation crossection of dye in microdroplet cavity; besides,the range of oscillation spectra distributed widely,and the spectral lines appear other oscilases. We compare the experimental result with the prediction of theory, we find the nearly matched explanation.