Soft-mode onset of coherent oscillation is revealed in a semilinear cavity with two counterpropagating pump waves. From the dynamics of the oscillation intensity and the dynamics of the grating decay with the feedback applied, critical behavior is detected: Both the characteristic time of oscillation onset and grating decay time go to infinity exactly at the threshold coupling strength. A conclusion is made about the similarity of this type of oscillator to the second-order phase transition.
© 2002 Optical Society of America
(190.4380) Nonlinear optics : Nonlinear optics, four-wave mixing
(190.5040) Nonlinear optics : Phase conjugation
(190.5330) Nonlinear optics : Photorefractive optics
(230.4910) Optical devices : Oscillators
Pierre Mathey, Pierre Jullien, Serguey G. Odoulov, and Oksana A. Shinkarenko, "Second-order optical phase transition in a semilinear photorefractive oscillator with two counterpropagating pump waves," J. Opt. Soc. Am. B 19, 405-411 (2002)