提出了一种光照直接改变光纤布拉格光栅（FBG）直流折射率调制强度引入相移的方法。仿真和实验表明，利用该方法可以在FBG上产生任意相移量。对利用该方法设计的相移FBG和传统离散相移FBG的性能进行了比较，表明两者具有相近的反射谱特性。针对光码分多址应用，制作了7位、63位码片的时域相位编解码器，测试结果表明其具有良好的编解码性能，从而证明了该种方法可用于制作多相移光栅。该方法在FBG中引入相移时不需要相位掩模板、制作工艺精度低，因此在灵活性、简单性和制作成本方面有一定的优势。

A new way of achieving phase shifts in fiber Bragg grating (FBG) by increasing direct current refractive index of the FBG is proposed. Simulation and experimental results show that arbitrary phase shifts can be achieved by the presented method. Comparison between the proposed direct-current phase-shift and traditional discrete phase-shift FBG is made, which shows a good agreement. 7- and 63-chip optical code-division multiple-access en/decoders are fabricated. The fine en/decoding performance verifies the feasibility of fabricating multi-phase shifted FBG by the proposed method. High-precision and phase mask are not required in fabrication. This method has advantages in cost-effectiveness, flexibility and simplicity compared to traditional ways.