高功率、高光束品質雷射的需求隨著工業與軍事應用日益增加，單模光纖因為本身的限制，使得雷射輸出被限制在萬瓦等級，因此要得到更高功率，就必須利用多單元光束合束方式實現，目前研究使用光譜合束中的多層電介質光柵的方法居多，此元件需要高合束效率及高雷射誘導損傷閥值，但國內長久以來缺乏高雷射誘導損傷閥值鍍膜技術，為了掌握高功率雷射應用領域所必備的關鍵技術，本計畫基於過去的研究基礎下，將薄膜製程最佳化，並建立相關實驗數據，掌握關鍵技術之參數，藉由兩方面提升雷射誘導損傷閥值，一方面為進行超低吸收薄膜材料之製程參數建立，從鍍膜成長機制、基板溫度、材料的選擇、基板平整度的選擇以及基板的清洗著手，另一方面從膜層結構之電場匹配設計，透過將電場峰值移出膜層交界處，來提高抗高能量的能力，並控制膜層堆疊的膜厚誤差，來完成高雷射誘導損傷閥值鍍膜技術的任務，再經由FDTD計算軟體來提高合束的效率，實際製作多層電介質光柵，完成高合束效率高雷射誘導損傷閥值的多層電介質光柵來提供高功率雷射使用。預計實際製鍍99.99%的高反射鏡，在532nm脈衝雷射的雷射誘導損傷閥值大於10 J/cm2，多層電介質光柵的合束效率在90%以上以及1064nm脈衝雷射的雷射誘導損傷閥值的量測大於6 J/cm2。 ;Increasing of industrial and military applications needs the high Power and high Beam Quality Laser. Single-mode optical fiber has been limited to a few million watts for its own limitations. Therefore, it is necessary to use multi-unit beam combination method to get higher power laser. At present, the most widely used method is multilayer dielectric grating in spectral beam combining, which requires high beam-forming efficiency and high laser induced damage threshold. However, there is a lack of high laser induced damage threshold coating technology in Taiwan. In order to have the key technologies of high-power laser applications. This project optimizes thin film manufacturing process and establishes relevant experimental data to grasp the key technical parameters based on the past research. Using two way to increase laser induced damage threshold, the first is to establish the process parameters for the ultra-low absorption thin film material, from the plating growth mechanism, substrate temperature, material selection, substrate flatness selection, and substrate cleaning proceed. The second approach is design the electric field to match the film structure to move the peak of the electric field out of the boundary of the film surface to increase the resistance to high energy, and to control the film thickness error. The FDTD calculation software will use to improve the efficiency of the beam combination. Multilayer dielectric grating with high beam-forming efficiency and high laser induced damage threshold will fabricate to provide high-power laser. The reflectance of high reflection mirror is 99.99% and laser induced damage threshold is more than 10 J / cm2 at 532 nm pulsed laser. The beam-forming efficiency of multilayer dielectric gratings will more than 90% and laser induced damage threshold is more than 6 J / cm2 at 1064 nm pulsed laser.
