神光-Ⅲ原型装置预放钕玻璃高增益自激振荡的分析与抑制

Analysis and Control of Self-Excitation Oscillation in TIL of the SG-Ⅲ Facility

在高功率激光装置的预放系统中,高增益放大单元提供超过106的增益倍数,极易形成自激振荡,降低光束放大倍数、破坏光学元件。基于高功率固体激光系统自激起振的主要判据,通过分析钕玻璃高增益系统损耗与增益的大小,研究了神光-Ⅲ原型装置高增益放大单元的自激振荡问题。分析了系统可能存在的自激振荡腔,指出系统可能存在3个起振的振荡腔。通过采取钕玻璃端面引入倾角、适当的光路调节、加隔离和电光开关等方法,在一定程度上抑制了自激振荡,进行了相应的实验验证,实验结果表明通过上述措施基本消除了自激光问题。

In the pre-amplifier of high power laser facilities, more than 106 gain is produced by the high gain amplifier, in which self-excitation oscillation would be easily formed. Based on the theory of self-excitation oscillation, the gain and loss in the system are analyzed, and the self-excitation problems in the high gain amplifiers of TIL of the SG-Ⅲ facility are studied. There self-excitation cavities would possibly exist in the system. Using the methods including tilting the ends of Nd： glasses, adjusting the beam, utilizing isolations and electro-optical switches, the self-excitation oscillation is controlled. These suppression methods are validated in experiments.