Achieving tunable bistability through photonic multilayers doped by unmagnetized plasma and coupled nonlinear defects

Using the modified transfer matrix method, we introduce one kind of one-dimensional photonic mutilayers with two coupled nonlinear defects separated by a linear plasma layer. The switching threshold values can be greatly reduced just by choosing the proper parameters of the linear middle plasma layer. We find the higher threshold value can be independently modulated by plasma density, while the lower threshold value can be changed independently by varying collision frequency. Due to its low incident intensity and highly compact structure, our design may be applied to microwave devices such as microwave isolator.