利用工作在盖革(Geiger)模式下的单光子探测器(single-photon-counting module,SPCM),采取单个探测器直接对光子计数的方法,对相干光场及热光场的光子数统计性质进行了测量和分析.通过改变计数率,调整分辨时间,系统地研究了光场二阶相干度测量值受实验条件的影响.结果表明,在综合考虑系统中的各种因素对测量影响的情况下,通过选择合适的测试条件,可以利用单个单光子探测器直接探测的方法快速确定一个待测光场的二阶相干度.实验表明在实测计数率为109kc/s,分辨时间范围为2^8ns-2^12as的条件下,该系统能很好地揭示相干光场和热光场的光子统计性质.
Photon statistical properties of coherent field and thermal field are experimentally studied by means of direct photon counting using only one single-photon-counting module (SPCM) operating in Geiger mode. The second-order degree of coherence as affected by photon counting rate and selected resolution time is investigated systematically. By taking into account all the experimental factors which can influence the g, the second-order degree of coherence of an unknown optical field can be determined quickly and simply via single SPCM when choosing proper detecting conditions. In our experiment, when the counting rate is about 109 kc/s and the resolution time varies from 2s ns to 212 ns, the measured results can reliably reflect the different second-order degree of coherence of coherent and thermal fields.