为了根据外界条件的变化自动进行增益调整，引入了中间级接入掺铒光纤放大器，它具有两级放大功能，增益在一定范围内可调，且能自动根据系统的变化调整自身的增益，使其满足不同条件的应用需求。采用自动增益校准的方法，对其原理进行了理论分析和实验验证，取得了中间级接入掺铒光纤放大器的增益校准及验证数据。结果表明，自动增益校准数据具有较高的准确性。这一结果对掺铒光纤放大器实现快速、准确的自动增益控制是有帮助的。

In order to adjust the gain automatically under different environmental conditions, an erbium-doped fiber amplifier (EDFA) with mid-stage access was introduced, which had two amplifier stages and variable gain within a certain range. To achieve the purpose of automatic gain adjustment, the method of automatic gain calibration was adopted. After theoretical analysis and experimental verification, the data of gain calibration and verification of the EDFA with mid-stage access were obtained. The results show that the data of automatic calibration has high accuracy. This research is helpful for EDFA to achieve automatic gain control rapidly and exactly.