本論文研究具有平凹共振腔的軸向激發摻釹釔鋁石榴石被動Q開關雷射當共振腔組態改變時對雷射輸出特性的影響。實驗上我們觀察輸出功率、重複率、脈衝寬度等參數隨腔長改變的變化，研究中發現：雷射輸出在鄰近幾何穩定共振腔邊緣時會出現不穩定且有多橫模的現象產生，所以Q開關脈衝的不穩定性應與半球共振腔組態下功率、增益和損耗隨腔長的高度變化與多橫模間的交互作用有關。 In this thesis, we experimentally study the resonator-configuration dependent dynamics in an axially pumped passively Q-switched Nd:YAG laser with a plane-concave cavity. We observed the average output power, repetition rate and pulse width as a function of the cavity length at different pump power. Our investigation shows that the laser pulse train will fall into unstable when the cavity length is adjusted near the edge of the geometric stable resonator configuration. We also find that the laser tends to run into multiple transverse modes in this region. Therefore,the instability of Q-switched pulses is related to the interaction of multiple transverse modes around the hemispherical resonator configuration where they are subject to a significant cavity-length-dependent variation of gain or loss.
