  In this paper, we present a theoretical analysis of the optical bistability
in a metallic silver-Bragg reflector structure by embedding bilayer MoS2 at the
visible band. The nonlinear OB is achieved due to the nonlinear conductivity of
the bilayer MoS2 and the excitation of the optical Tamm state at the interface
between the silver and the Bragg reflector. It is found that the hysteresis
behaviour and the threshold width of the OB can be effectively tuned by varying
the incident light wavelength. In addition, the optical bistable behaviour of
the structure can be adjusted by varying the position of the MoS2 inset in the
defect layer, incident angle and the structural parameters of the spacer layer.
Although the current threshold cannot be commercialized, we believe that this
solution will provide a meaningful path reference for low threshold bistability
in the visible light band.
