毫焦耳級準連續式二極體側向激發被動式Q開關雷射的設計與應用

Abstract

高峰值功率人眼安全脈衝雷射在工業界中已被廣泛使用。在本論文中，我們分別利用Nd:YVO4和Nd:YLF為增益介質搭配Cr4+:YAG為飽和吸收體，在經過二次閥值的理論分析後，採用近半球腔及二極體側向激發的架構來達成高峰值功率之被動式Q開關雷射。接著以此被動式Q開關雷射為基礎，加入KTP晶體進行頻率轉換，透過光參數振盪的技術將1微米的波長轉換到1.5微米人眼安全雷射的波段。以Nd:YVO4為增益介質的實驗中，可產生能量為3 mJ、峰值功率達100 kW的脈衝雷射；進行光參數振盪後得到能量為1.4 mJ、峰值功率為100 kW的人眼安全脈衝雷射。改以Nd:YLF為增益介質後，可得能量達20 mJ、峰值功率為950 kW的脈衝，經過光參數振盪後更可得能量達10 mJ、峰值功率為600 kW的脈衝雷射。

High-peak-power eye-safe pulsed lasers have been widely used in industry applications. In this thesis, we utilize the Nd:YVO4 and the Nd:YLF crystals as gain mediums with the Cr4+:YAG crystal as the saturable absorber to explore a passively Q-switched laser. Through the theoretical analysis of second threshold condition, we adopt the design of nearly hemispherical cavity and the diode-side-pumping configuration to realize the high peak power output. Futhermore, we demonstrate the eye-safe laser by adding the KTP crystal to perform the extracavity optical parametric oscillation for converting the lasing wavelength from 1 um to 1.5 um. In the experiment of Nd:YVO4 PQS laser, the output pulse energy reaches 3 mJ and the peak power is 100 kW. For the OPO operation, we obtain a 1.4-mJ output pulse energy with the peak power of 100 kW. On the other hand, the output pulse energy of 20 mJ with the peak power up to 950 kW can be attained by utilizing the Nd:YLF crystal as the gain medium. We further realize the eye-safe laser with pulse energy of 10 mJ and peak power of 600 kW through the OPO operation.