The Refractive Index Change and Self-Defocusing Effect of Methyl Red Doped Polymer

The absorption spectra of trans and cis states of the methyl red doped poly(methyl methacrylate) film are measured separately. The refractive index change distribution of the sample film is determined using the Kramers–Kronig relation along with the absorption spectrum data. The self-defocusing properties of a methyl red sample at 441.6 and 535 nm are investigated and the results indicate a significant optical limiting property.