提出一种对光脉冲直接相位调制进行光谱展宽的方法，对调制深度、调制信号宽度、同步精度和不同调制信号形状对输出光谱的影响进行了数值模拟。模拟结果表明，调制深度越大，调制信号宽度越小，对光谱的展宽效果越明显，单次调制展宽量越大；不同的调制信号宽度对同步精度有不同的要求，调制信号越窄，对同步精度要求越高；相比于抛物线型调制信号，正弦调制信号会带来光谱两侧明显的幅频调制，降低脉冲可压缩性和再压缩信噪比。实验结果与模拟数值结果相符。

A method to broaden the spectrum by direct phase modulation is proposed. The effects on the spectrum of modulation depth,modulation signal width, synchronization precision and different signal forms are investigated by numerical simulations. The results show that deeper modulation and more narrow modulation signal width lead to a more obvious effect and a broader spectrum of single modulation; different modulation signal widths require different synchronization precisions, and the narrow signals need a high-precision synchronization; compared to the parabolic signal, sinusoidal signal can lead to an obvious frequency modulation to amplitude modulation, which can bring down the compressibility and the signal to noise ratio. The experiment results of the central wavelength match well the simulation results.