用双光源相位共轭型非相干光时间延迟简并四波混频测量超快速过程

MEASURING ULTRAFAST PROCESSES USING TIME DELAYED FOUR WAVE MIXING IN PHASE CONJUGATION CONFIGURATION WITH INCOHERENT LIGHT FROM TWO SOURCES

本文提出用双光源相位共轭型非相干光时间延迟简并四波混频测量失相时间和布居弛豫时间的理论,并对其应用进行了讨论.

In ordinary time delayed four wave mixing with incoherent light, the forward, backward pump and probe beams are from one source. In phase conjugation configuration, signal Is(τ) is from two dynamic gratings formed by interference of probe beam with forward or backward pump beams respectively. The complicity of the relation betwean Is(τ) and dephasing and depopulation times makes fitting error large.We propose in this paper a two source method, where backward pump beam is from a source independent of the one for forward pump and probe beams. In this case only one dynamic grating may be formed in the medium.If depopulation time T1 and dephasing time T2 of the medium are much longer than the coherent time of the light source τc, it can be shown thatfor the medium with extremely wide inhomogeneously broadened absorption line. whilefor the medium with homogeneously broadened absorption line. If T1,τc>>T2 on the other sideT2, T1 and τc may be obtained by fitting Is.(τ) with these formulas.