DISPERSION OF THE INDUCED OPTICAL NONLINEARITY IN RHODAMINE 6G DOPED BORIC-ACID GLASS

The spectral dispersion of the induced optical nonlinearity has been investigated in an optically thick sample of rhodamine 6G dye doped boric acid glass. The light-induced changes in the absorption coefficient were measured over a wide range of frequencies. The corresponding changes in the phase dispersion were calculated by the Kramers-Kronig transformation. The changes in the complex refractive index so obtained were used to calculate the diffraction efficiency within Kogelnik's model. The results show a good agreement with the measured diffraction efficiency of a nondegenerate probe, The analysis revealed the presence and the significant role of excited state absorption in the dynamic grating diffraction process.