- 學位論文
輻射捕捉與共振腔相關之紅寶石螢光特性
Radiation Trapping And Cavity-Dependent Fluorescence Of Ruby
摘要
我們研究紅寶石晶體未加共振腔與加共振腔的螢光特性: 1.在未加共振腔且當幫浦功率不變時，使用適當的收光系統測量得知在幫浦區域的生命期較短而螢光輸出功率較大，而在非幫浦區域的生命期較長而螢光輸出功率較小。改變幫浦功率時，在幫浦區域的幫浦功率較大而生命期較小，我們認為是幫浦功率較大時，幫浦區域的基態能階的離子較多被打到激發態，造成基態離子減少以致再吸收(輻射捕捉)的機率減少，所以生命期增加較少。 2.加共振腔且腔長在半共心腔附近的實驗中，在低功率幫浦的情況下，縱向的螢光生命期在半共心腔處的螢光生命期最短，非穩腔時的生命期最高，腔內加入光圈或移除輸出耦合鏡以破壞共振腔效果，得到的縱向生命期與腔長無關，生命期變短的確是來自共振腔的影響。
並列摘要
We study the lifetime of a ruby crystal in the absence and presence of optical cavity. First, we obtain the shorter lifetime and the larger collected power in the pumped region than those of the unpumped region when the ruby absorbs the same power without cavity with proper apparatus. We also find that the lifetime is decreased when the pump power is increased for the pumped region. We ascribe that there are more ions from ground state to the excited state for the larger pumping power, thus decreasing the density of ions in the ground state and deceasing the probability of radiation trapping (reabsorption). Second, when the crystal is located inside the hemispherical cavity and when the pumping power is much smaller than the lasing threshold, we obtain the shortest lifetime in the axial direction for the hemispherical cavity and the largest axial lifetime in the unstable cavity. When the cavity effect is broken by using an aperture inside the cavity or by removing the output coupler, we obtain the axial lifetime is independent of the cavity length. This means the lifetime is surely cavity-dependent.