为了得到高性能的多载波光源，研究了射频信号中不同相位差对光多载波的影响.通过理论分析可得，随着相位差从90°降至0°，光多载波性能会逐渐变差，但是相位差偏与90°相差不大时，性能不会下降太多.实验中通过移相器改变相位差，使相位差为90°,45°,0°，得到循环前IQ调制器的输出光谱，并对比循环后光多载波性能.实验结果显示，相位差为90°时，循环前IQ调制器输出为较好的单边带光谱，循环后输出50条平坦稳定光多载波；相位差为45°时，光多载波质量变差；相位差为0°时，得不到光多载波.因此，射频信号相位差为90°时，光多载波的性能最佳，随着相位差变小，性能下降，但是相位差为45°时，产生的光多载波仍可应用于光通信.

In order to generate a high quality multicarrier, the phenomenon caused by different phase deviation of radio frequency was analysed. In this paper, the theoretical analysis revealed that the quality of multicarrier would deteriorate gradually when the phase deviation decreases from 90° to 0°. But when phase deviation is slightly different from 90°, the quality of multicarrier is good enough for the application of optical communication. In the experiment, the qualities of multicarriers with phase deviation of 90°, 45° and 0° were compared. The best performance is obtained at 90°. Under the 45° phase deviation, fifty carriers can also be otainted, but the quality decreases slightly that is good enough to apply to optical communication. And a multicarrier under 0° phase deviation cannot be obtained.