Investigation of the optical bistability in the PMMA polymer doped with MNA

The optical bistability (OB) of PMMA polymer doped with 2-Methyl-4-Nitroaniline (MNA) thin films on Mach-Zehnder interferometer nonlinear ring cavity with applied external feedback was investigated in five thicknesses. The measurements were performed at 532 nm using a Nd:YAG CW laser with irradiation of 300 mW. An optical bistability hysteresis was obtained because of charge transfer in benzene ring in MNA's structure. It is demonstrated that although, the gain of optical bistability improved using external feedback for thinner samples. While, in thicker samples, the local thermal effect decreased the gain and had negative effect on OB.