Photo-induced excitations in the tris-(bipyridyl)Ru(II)-catalyzed Belousov-Zhabotinsky reaction are studied numerically using the Oregonator model, modified to describe photosensitivity. An abrupt change in bromide concentration induced by a pulse-light perturbation causes a large excursion. The mimimal light intensity for initiating an excitation decreases while the system approaches to a bifurcation point. This study provides an alternative explanation for a recent experimental research.