为了提高光纤光栅外腔半导体激光器的激射波长准确性，根据光纤光栅外腔半导体激光器的相位条件确定光纤光栅外腔半导体激光器的激光纵模分布后，采用数值模拟的方法研究了光纤光栅外腔半导体激光器的激射波长随光纤端头到有源区之间空气间隙长度的变化。结果表明，光纤光栅外腔半导体激光器的激射波长随着空气间隙长度的变化围绕着光纤光栅的布喇格波长波动，波动的最大幅度随外腔长度的增加而减小。因而当外腔长度一定时，可以通过微小的调节空气间隙的长度使激射波长精确定位于光纤光栅的布喇格波长处。

In order to control accurately the lasing wavelength of the fiber grating external cavity semiconductor laser(FGECSL),after determining the mode distribution based on the phase condition,the influence of the air gap between the head of fiber and the front face of F-P LD on the lasing wavelength of FGECSL was through numerical simulation. The results show that the variation of the air gap will result in the lasing wavelength rippling around the Bragg wavelength of fiber grating(FG),and the amplitude of fluctuation becomes smaller with the increase of the external cavity length. For a fixed length of external cavity,the lasing wavelength can be accurately located in the Bragg wavelength of FG through adjusting the air gap carefully.