Correlations in optical fluctuations in multiple scattering medium and its applications

我们研究了多重散射介质中光波动的相关性，并发展了其在光子学中的应用研究了多散射介质中时空分辨非线性相关测量中的相干耦合效应。在这种测量中，将两束激光注入到介质中，测量非线性光信号的总强度作为两束激光之间的相对时间延迟和相对空间分离距离的函数。我们研究了相干耦合效应的形式因子作为两束激光之间的频率和波矢量差的函数。形状因子显示了多重散射介质内部散斑波动的一个有趣特征，即形状因子不与输运平均自由程成比例，但即使在反射几何中也与样品厚度成比例多散射介质中持续烧孔研究了光反应介质和多散射介质中持续烧孔的发展。在这种烧孔过程中，写入激光束通过光反应过程在介质内部记录体积散斑图案，然后测量读取光束激发的发光强度作为写入光束和读取光束之间的频率或波矢量差的函数。时间发展反映了介质内部散斑强度波动的统计。其中一个显著的结果是最大孔深为~ 0.26。测量了孔洞形状和宽度与样品厚度、输运平均自由程和吸收长度的关系，实验结果与先前报道的基于扩散近似的理论计算结果吻合良好。

We investigated correlations in optical fluctuations in multiple scattering medium and developed its applications in photonics.[1] Coherence coupling effect in a multiple scattering mediumCoherence coupling effect in a space and time resolved nonlinear correlation measurement in a multiple scattering medium was investigated. In this measurement two laser beams are injected onto the medium and the total intensity of nonlinear optical signal is measured as a function of the relative time delay and the relative spatial separation distance, between two laser beams. We examined the form factor of the coherence coupling effect as a function of the frequency and the wave vector differences between two laser beams. The form factor shows an interesting feature which is characteristic to the speckle fluctuations inside the multiple scattering medium, that is, the form factor does not scale with the transport mean free path but it scales with the sample thickness even in the refection geometry.[2] Persistent hole burning in multiple scattering mediaTime development of a persistent hole burning in photo-reactive and multiple scattering media was investigated. In this hole burning, a writing laser beam recodes volume speckle pattern inside the medium through the photo-reactive process, then, the luminescence intensity excited by a reading beam is measured as a function of the frequency or the wave vector difference between the writing and the reading beams. The time development reflects the statistics of the intensity fluctuations in the speckle inside the medium. One of the striking results is that the maximum hole depth is 〜0.26. The dependence of the hole shape and width on the sample thickness, transport mean free path and absorption length were measured and experimental results show good agreement with a previously reported theoretical calculation on the basis of a diffusion approximation.