在高功率准分子激光系统中，由于介质的高增益和非存储特性，自发辐射放大(ASE)成为影响系统输出对比度的关键因素。在角多路主振荡功率放大器(MOPA)激光放大链中，为抑制ASE，采用了电光开关和增益控制相结合的方式，在第一放大级后置入了电光削波开关，并利用检偏器另一偏振分量作为控制光束，对下一放大级进行增益控制。构建了光路，进行了原理性实验研究，并在第二预放大级中获得了403001的信号对比度。采用该方法的优点是在主光路中引起的能量损耗小, 且降低了对破坏阈值的要求。电光开关和增益控制相结合共同实现了前两级预放大器的ASE抑制。

In high power excimer laser system, due to high gain and nonstorage medium, amplified spontaneous emission (ASE) is the key factor impacting on the signal contrast of the system output. In angular multiplexing master oscillator power amplifier (MOPA) laser amplifier chain, combination of the electro-optical switch and gain control method is used to suppress ASE. An electro-optical (E-O) switch is plugged after the first amplifier, and the other polarizer component of the analyzer is used for controlling the light beam and as gain controlling beam of the next amplifier. The optical path is constructed, principle experiments are carried out, and signal contrast up to 403001 is obtained in the second pre-amplifier. The advantages of this method are less energy loss and lower damage threshold request. The combination of E-O switch and gain control method gives a good solution to the ASE suppression of the first two pre-amplifiers.