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研究光子晶体光纤中超连续谱的时间相干性和空间相干性.采用时间分辨率为飞秒级的迈克尔逊干涉仪,通过在零点附近改变两光路的延迟,对超连续谱的复时间相干度曲线进行测量,得到超连续谱的相干长度为3.71μm.采用同样系统对飞秒泵浦源的复时间相干度曲线进行测量,计算得到其相干长度为62.24μm.通过计算光程差为零点处的互相干度得到超连续谱的空间相干度为0.77,表明光纤小的发光面积使其空间相干性较好.利用准直透镜和分光棱镜将光纤输出的光束进行分光,得到超连续谱中几种不同颜色的输出光谱及对应的脉冲序列,其脉冲序列与泵浦激光有相同的重复频率.
The temporal coherence and spatial coherence of supercontinuum in photonic crystal fiber are studied.The Michelson interferometer with time resolution of femtosecond is used to change the complex temporal coherence curve of supercontinuum by changing the delay of two optical paths in the vicinity of zero point The coherence length of the supercontinuum was 3.71μm. The same system was used to measure the complex time-dependent coherence curve of the femtosecond pump source, and the coherence length was calculated to be 62.24μm. By calculating the optical path difference at zero The spatial coherence of the supercontinuum spectrum obtained by mutual coherence is 0.77, which shows that the small light emitting area of the fiber makes its spatial coherence better. The collimated lens and dichroic prism are used to separate the light beam output from the fiber to obtain several kinds of supercontinuum The output spectra of different colors and corresponding pulse sequences have the same repetition frequency as the pump laser.