研究了一种新型的短腔铒镱共掺单纵模调频光纤激光器，推导了该类光源利用零差检测法时功率谱密度的理论表达式，进行了数值模拟，计算出了最大频偏量。激光器是由一段4cm长的铒镱共掺光纤和两个窄线宽光纤布拉格光栅构成，通过对靠近抽运端光栅的长度调制实现了激光的频率调制。激光器线宽小于400 kHz，输出功率大于3mW，最大频偏可以达到55MHz，最大频偏量的实验结果与理论分析一致。

A novel short cavity Er-Yb codoped single-longitudinal-mode frequency modulated fiber laser is demonstrated. The theoretical spectrum expression of frequency modulated laser using delayed self homodyne technique is deduced and simulated. This laser is mainly fabri-cated by a 4 cm long Er-Yb codoped fiber and two spectrally narrow fiber Bragg gratings. To realize the purpose of frequency modulation,the grating near the input of pump is modulated in length. The output power of the laser is more than 3 mW,linewidth is less than 400 kHz and maximum value of the laser optical frequency deviation can reach 55 MHz.