由相干度理论和准单色光理论出发研究了发光二极管(LED)的时间相干与空间相干特性,并采用时间分辨为亚飞秒的迈克尔逊干涉仪对LED的相干度进行了测量记录。由记录所得的干涉图计算得到LED的发射光谱、相干时间及时间相干度;并通过比较其可见度和时间相干度推算出其空间相干度;最后提出由空间相干度计算LED发光面积的方法和使用LED光源测量材料中超快弛豫过程的可能性。分析了实验中的误差并提出修正方法,为采用LED作为稳态与时间分辨光谱光源提供了必要的理论与实验依据。

The temporal and spatial coherence of light emitting diode (LED) is studied by Michelson interferometer with subfemtosecond time resolution. LEDs′ spectral characteristics and coherence time are measured, and their emitting area is estimated by LEDs′ interference signal. Systematic errors in the experiments are discussed and the solutions to reduce the errors are suggested. Results show that LED can be applied as a light source for stable and time resolved spectroscopy.