Phase wave between two oscillators in the photosensitive Belousov-Zhabotinsky reaction depending on the difference in the illumination time.

To investigate the nature of the phase wave between two connected oscillators, the photosensitive Belousov-Zhabotinsky (BZ) reaction was examined for two connected circular reaction fields, which were drawn by using computer software and then projected on a filter paper soaked with BZ solution by using a liquid-crystal projector. The difference in the time at which illumination was terminated between the two circles (Deltat(0)) was changed to control the time at which the phase wave was induced. When Deltat(0) was small (0-3 s), the phase wave normally propagated on the two circles in one direction. In contrast, when Deltat(0) was large (6-10 s), the velocity of the wave decreased near the intersection of the two circles. These different features are discussed in relation to the excitability of the circles and Deltat(0). The experimental results were qualitatively reproduced by a numerical calculation based on the modified three-variable Oregonator model that included photosensitivity.