Purpose. We study of the dynamics of atomic-molecular conversion in a Bose-Einstein condensate. Methodology and Approach. The paper explores the behavior of the potential energy of some nonlinear oscillator as a function of the magnitude of the photon density of the second pulse. Results. An equation is found for the density of photons of the second pulse in the system of Bose-condensed atoms and molecules. Theoretical and Practical Implications. We have obtained the solutions and found critical values of parameters at which evolution modes change.