I have taken a multilayer structure ( AB)nD(BA)n where high refractive index layer A and defect layer D is Kerr nonlinear and low refractive index B is linear. I applied transfer matrix method and found shifting of resonance peak(due to defect) by intensity in transmission curves. But I am not getting the optical bistability curve (between transmission and intensity).Is there any specific conditions for optical bistability or simple TMM method is insufficient for calculation of optical bitability?