在理论上分析了飞秒脉冲泵浦的Ⅱ类共线的自发参量下转换信号光与闲置光光谱的分布特征。由于非线性晶体色散的影响,信号光与闲置光光谱分布不完全相同,且这种差异会随着泵浦谱宽的增加而加大。同时在实验上测量了Ⅱ类共线匹配的下转换信号光与闲置光的光谱分布。将理论分析与实验结果进行对比,变化趋势是一致的。本文对连续变量单光子探测中的模式匹配及光子对四阶干涉的条纹可见度等相关量子光学测量有一定的指导意义。

Spectrum distribution of spontaneous parametric down-conversion is discussed in type-Ⅱ phase matching process with a Femto-second pulse laser pump.The spectrum distribution of signal and idle beams are different from each other and the differences vary with the width of Femta second pulse laser pump.We have also measured the spectrum distribution of type-Ⅱ phase matching BBO crystal＇s spontaneous parametric down-conversion beams.The results coincide with theorctical analysis.They are useful when measuring the light non-classical property with Femto-second pulse balance homodyne detecting system.