光纤放大器热效应引起的相位噪声理论分析

光纤放大器相位噪声的探测和校正是光纤激光器阵列相干合成的关键技术，热效应是引起光纤放大器相位噪声的主要来源。理论分析了泵浦光开启到稳态过程中光纤放大器掺杂光纤的温度变化，以及对应的光纤放大器相位变化。通过数值计算发现，泵浦光在开启后，光纤放大器的掺杂光纤温度迅速升高，相位变化剧烈，在约10 s后达到稳态，此后泵浦光的能量不稳定。这表明，泵浦光的能量不稳定是引起光纤放大器相位噪声的最主要因素，通过稳定泵浦光电流可以降低光纤放大器的相位噪声。

Theoretical study on the phase noise by thermal effects in fiber amplifier

It is the key technology to detect and correct the phase noise of the fiber amplifier in coherent combining beam, the main source of phase noise in the fiber amplifier is the thermal effects. Theoretical analysis are presented,which are the pump-induced temperature change and the associated thermal phase shift occurring in a fiber amplifier from the pump turning on to steady state . The results show that the temperature and the phase of the fiber amplifier quickly change when pump light is unstable. Therefore, the main reason ,which causes the phase noise in the fiber amplifier,is the unstable energy of pump light,and the phase noise in the fiber amplifier can be reduced by stabilizing the current of pump light.