以掺釹晶體產生不同波長之高能量脈衝雷射及其波長轉換

Abstract

全固態雷射和非線性光學波長轉換技術的研究不僅具有重要的學術意義，更具有重要的應用價值。隨著高功率的雷射二極體的發展，高能量的固態雷射已成為目前的重點研究之一。各類雷射增益介質具有不同多個斯塔克分裂能級的譜線，透過實現雷射增益介質本身具有的各級譜線之波長，再結合非線性光學波長轉換技術可拓寬雷射的波長範圍與應用領域。本文是以摻釹的雷射晶體作為研究，實現低增益譜線的準三階雷射波段和人眼安全雷射波段。除了使用傳統的晶體式飽和吸收體作為被動式Q開關元件，我們針對不同波段設計合適的半導體材料製作成量子井飽和吸收體，以產生高效率和高能量的脈衝雷射。半導體材料除了作為雷射腔內的飽和吸收體，我們發展半導體週期性材料作為抑制強增益譜線的一種新穎元件，此元件對腔內的損耗很低，對於實現高效率的低增益譜線之雷射相當有價值。摻釹的雷射晶體在最強增益的波段1.0 □m已經有相當成熟和穩定的脈衝雷射研究，對於各類的波長轉換技術是重要的關鍵之一。我們利用腔內的光學參數振盪器，產生在1.5 □m附近的人眼安全波段雷射。以理論分析腔內的光學參數振盪器之優化，並以實驗佐證，發展高效率、高能量的人眼安全波段雷射及雙波長雷射。透過雷射共振腔體的設計，利用些微的熱透鏡效應去發展不穩定的雷射腔體，有效地改善雷射光束品質。

As the development of laser diodes, they are helpful for solid-state lasers. High-pulse-energy solid-state lasers have been the main researches. There are many laser transition lines in each laser medium. Based on the generation of various fundamental laser wavelengths and nonlinear wavelength conversions, solid-state lasers can be applied in more fields. In the thesis, Nd-doped crystals are chosen to be the laser media to realize the low-gain quasi-three-level lasers and eye-safe lasers. A good quasi-three-level laser in Q-switched regime is potential and helpful for developing pulsed blue laser. Besides the conventional bulk saturable absorbers, we develop the suitable semiconductor materials for various laser transition lines to make a QWs saturable absorber. Efficient, high-pulse-energy Q-switched lasers are generated. In addition, semiconductor materials are not only used to be the absorber for passively Q-switched laser, but also to be the novel intracavity selective absorbers used for suppressing the higher gain lines. On the other hand, Nd3+-doped pulsed lasers at 1.0 μm have been maturely developed for many years and possess superior performances. We utilize the Nd3+-doped pulsed lasers at 1.0 μm as the pump lasers to generate eye-safe intracavity OPOs. Based on the numerical analysis and cavity design, we are devoted to generate highly efficient high-energy eye-safe lasers.