Subpicosecond Accumulated Photon Echo with Incoherent Light

概要

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An analytic theory and experimental studies of the accumulated photon echo ispresented. We define a temporal correlation function G of the excitation field E(t) asG(r,t)=(1/T.) 5: dt'E(t -t')E(t -t' -r)-cxp( -Z'/7'.), where T. is the populationrelaxation time of the sample, and call the width of G with respect to r a temporal correlation time f.(Z). It is proved that the echo intensity is written by the temporal cor-relation functions when (1) T, and the duration of the excitation light r. are muchlonger than f.(t) in order to make the function (;(r, t) well-defined, (2) T. and r. aremuch longer than the homogeneous dephasing time T., and (3) one can find a time in-terval At such that G(r, t) does not change much between t and t-FAt, where At>>f..Then we can show that the time resolution of the accumulated photon echo is determined by the averaged t.(t) over an interval of the integration of the echo signal. Thisdiscussion is valid for any excitation source if the above conditions are satisfied, andapplies to almost all cases of the practical accumulated photon echo experiment. Adiscussion is also made on the spurious spike on the echo decay curve near zero delaytime that appeared in an experiment with a high time resolution in Nd"-dopedsilicate glass. Itis shown that the most probable cause for this spike is uncorrelated in-homogeneous broadenings of the resonant lines of neodymium ions.
社団法人日本物理学会の論文
1987-06-15