Physical Review LettersComment on ‘‘New nonphotorefractive mechanism for two-beam coupling in a crystallographic-cut photorefractive crystal’’С. И. СтепановPublished Aug 13, 1990• 3 citationsPublisherAbstractA Comment on the Letter by G. Khitrova et al., Phys. Rev. Lett. 62, 1110 (1989).Received 19 March 1990DOI:https://doi.org/10.1103/PhysRevLett.65.935©1990 American Physical SocietyDOI10.1103/physrevlett.65.935