为了增大光束的填充因子及提高放大器的能量转换效率,设计了一种新型的空间4程放大器,该放大器包括四组由凹面镜组成的空间滤波器,它们构成一个全像传递系统.由于有实焦点,放大器置于真空系统中.放大前,入射的高斯光束首先通过一个软边光阑和一个空间滤波器,被整形为高阶超高斯光束,然后在放大器中进行放大和像传递.钛宝石晶体置于各空间滤波器的像面和物面上.实验表明,该放大器结构稳定,可以保持良好的光束质量,远场焦斑达到近一倍衍射极限.

In order to improve the filled factor of beam and the conversion efficiency of amplifier, with reference to the technical integrated line of Shenguang-Ⅲ, a kind of new spatial four-pass amplifier structure is designed, which is made up of four pairs of spatial filters, in the Ti:sapphire CPA system. The spatial structure amplifier is put in a vacuum because there are real focus points in the amplifier. Before amplification, the input Gauss beam firstly goes through a diaphragm and then a static spatial filter with a pinhole, the beam is refitted into a 4th order super-gaussian beam. Then, the image of super-gaussian beam is relayed to the first spatial filter of amplifier. The Ti:sapphire crystal is put at the surface of image or object of the spatial filters for the sake of the good quality of the beam. With this amplifier structure, the beam quality keeps well without spatial modulation, and the far field of the amplifier output is close to the diffraction limit.