Ultrafast Measurement of Fluorescence Photons with Tow-Photon Interference

我们提出了一种双光子干涉的方法来同时测量超快光脉冲的相干时间和脉宽。飞秒测量将成为可能，对非常宽的波长区域的光脉冲，没有时间分辨率的限制，并在非常低的强度光子计数水平。迈克尔逊干涉仪的两个输出由两个探测器检测，并通过改变光程差来计算一致性。当径差为零时，计数率减小，产生相干时间宽度的窄倾角和脉冲宽度数量级的宽倾角。我们成功地测量了染料激光脉冲、来自细粉的散射脉冲、来自胶体乳液（稀释牛奶）的散射脉冲和尼罗蓝染料溶液在二甲苯胺中的荧光。作为测量的变化，在干涉仪的两个臂上放置了两个BaSO_4样品或乳剂样品。我们成功地单独测量了宽倾角，当我们想知道脉冲宽度（或脉冲形状）时，这是有利的。然而，到目前为止，这在荧光的情况下是不可能的。需要进一步调查以揭示原因。

We have proposed a two-photon-interference method to measure simultaneously the coherence time and pulse width of ultrafast optical pulses. Femtosecond measurement will be possible for optical pulses of very wide wavelength regions without limit in time resolution and at very low intensity photon-counting levels.Two outputs from a Michelson interferometer are detected by two detectors, and coincidences are counted by varying the optical path difference. When the path difference is zero, the counting rate decreases, and produces a narrow dip having the width of the coherence time and a wide dip having the width of the order of the pulse width.We have succeeded in measuring dye-laser pulses, scattered pulses from fine powder Basso scattered pulses from colloidal emulsion (diluted milk) and fluorescence of Nile Blue dye solution in dimethylaniline. As the variation of the measurement, two samples of BaSO_4, or the emulsion are placed in the two arms of the interferometer. We succeeded in measuring the wide dip alone which is favorable when we want to know the pulse width (or pulse shape) alone. However, it is thus far not possible in the case of the fluorescence. Further investigation is needed to reveal the reasons.