In this paper, the optical bistability in finite size one-dimensional coupled resonator nonlinear optical waveguide has been investigated. To calculate the bistable switching manner in five proposed structures, we use the linear and nonlinear transfer matrices with fixed point iteration method. Our results show that the threshold and domain of bistable switching answer depend on the defect region in one-dimensional coupled resonator nonlinear optical waveguides. Also, the best answer of switch takes place at the left and right edges of the photonic band gap of the structures depending on the defect regions. In fact, due to the presence of the photonic band gap in the slow wave system, the density of states of the electromagnetic fields is large at the photonic band edge and photonic defect modes and thus the group velocity is small, and the local field is enhanced. All these factors contribute to a significant decrease in the threshold of optical bistable switching devices.
