A paradoxical decrease in the generation threshold of high Stokes and anti-Stokes components of stimulated Brillouin scattering in water has been detected for the first time to our knowledge upon the displacement of the caustic of a focused laser beam from the bulk of water to air. The mechanism of generation of components caused by the four-wave mixing on counterpropagating beams when the water surface serves as the mirror of an induced cavity of a stimulated Brillouin laser is discussed. An upper bound R ≪ 0.02 has been obtained for the reflection coefficient R of distributed feedback at stimulated Brillouin scattering in water.

中文翻译：

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新型感应腔布里渊激光器

在聚焦的激光束从大块的水到空气的位移中，我们知道，这是首次发现水中的高斯托克斯和反斯托克斯分量受激布里渊散射的产生阈值自相矛盾地降低。讨论了当水表面充当受激布里渊激光器的诱导腔的反射镜时，四波混频在反向传播的光束上引起的成分生成机理。在水中受激布里渊散射时，分布反馈的反射系数R的上限R R 0.02 。