激光拍频信号光子到达时间间隔特性分析

为了得到周期激光拍频信号的频率,从理论上推导了光信号相邻光子到达时间间隔满足的概率密度函数(PDF),以数值计算为基础,对周期性激光拍频信号进行详细分析,得到了稳定光强信号和周期拍频信号光子到达时间间隔PDF曲线形状的差别,从该差别中能够获取信号的拍频频率。设计了验证实验光路系统,采用多像素光子计数器(MPPC)记录光子时间,对6、8、10、12MHz拍频信号进行探测,证明了理论分析的正确性。在光子计数频率为拍频频率1/5的条件下,得到较好的实验结果,估计两光束混合效率为0.65。以暗计数噪声为限制条件,分析了该方法能够探测到的最小拍频频率为0.2333MHz。

Characteristics Analysis of the Photons Arrival Time Interval of Laser Beat Signal

In order to get the frequency of periodic laser beat signal, the probability density function (PDF) of time interval between two successive photoelectrons is derived theoretically. The difference of the shape in the PDF curve between the beat signal and stable light signal is obvious, and the beat frequency can be derived from the difference. An experiment system is designed in which a multi-pixel photon counter (MPPC) is used to record the photoelectrons time of the beat signal with beat frequency of 6, 8, 10 MHz and 12 MHz to give a potent verification to the theory. The experimental result is even much better in the condition that the photons count rate is 1/5 of the beat frequency, and an estimation of the mixing efficiency can be obtain using the statistics method which is 0.65 in our experiment. In the limitation of the dark count noise of the MPPC, the minimum beat frequency of periodic signal is 0.2333 MHz detected using this method.