We have found that when interacting with a crystal of BaTiO3 and under certain conditions, a beam which originally does not produce a self-pumped phase conjugate (SPPC) wave may shift to the self-pumping state due to the influence of another beam. The two beams are incident on the photorefractive crystal at neighboring sides and they may be coherent or incoherent to each other. The phenomenon has been observed even when the two beams are alternately shining on the crystal, or are derived from different kinds of lasers.
