Abstract: According to the theoretical analysis of the general formulas determing the frequency response (P_a(F))/(N_e²P_ao)~F, it is proved that,just as in the case of plane configuration, the condition that the frequency response curves in the case of step configuration are almost symmetrical about the central frequency F=1 is still F₁+F₂=2. Based upon this argument, we detrmine, through systematical calculations, the largest Bragg bandwidth which can be obtained for various numbers of transducer pieces N_e. At the same time, we obtain the optimum design of acoustoptic Devices.