Bogdan A R, Prior Y, Bloembergen N
Opt Lett. 1981 Feb 1;6(2):82-3. doi: 10.1364/ol.6.000082.
Phase-matched four-wave mixing in sodium vapor with a helium buffer gas is carried out in a noncoplanar geometry. The directions of the four light beams remain nondegenerate even if all frequencies are equal. A sharp zerodifference frequency resonance in the intensity of the parametrically generated fourth beam by three incident beams is observed that is proportional to the square of the pressure of the buffer gas. A theoretical interpretation of this effect caused by elimination of destructive interference between two coherent pathways is presented.
在含有氦缓冲气体的钠蒸气中，非共面几何结构下进行了相位匹配四波混频。即使所有频率相等，四束光的方向仍保持非简并。观察到由三束入射光参量产生的第四束光强度中出现了尖锐的零差频共振，该共振与缓冲气体压力的平方成正比。本文给出了由消除两条相干路径之间的相消干涉所引起的这种效应的理论解释。
