Optical bistability in one-dimensional photonic band gap structure with nonlinear graded-index defect layer

The transmission property of a one-dimensional photonic band gap structure with a nonlinear graded-index defect layer is investigated. Using the transfer matrix method, we find that such a composite structure exhibits a bistability that is strongly dependent on the gradation profile and the width of the nonlinear defect layer. The switching threshold values can be greatly reduced just by properly choosing the gradation profile and the width of the nonlinear defect layer.