Effect of polymer host on third order nonlinear optical properties of newly synthesized organic liquid crystal

We report the investigation of third order optical nonlinearity of 2,4,6-tri-(p-hyptoyoxylphenyl) pyrilium tetraborate doped PMMA using nanosecond laser pulses at 532 nm wavelength by employing Z-Scan technique. To see the effect of polymer host, the results have been compared with the pure dopant. The material shows a large negative nonlinearity with real and imaginary parts of chi⁽³⁾ are - 3.31times10^-14 esu and 0.73times10^-14 esu respectively. Excited state absorption cross-section is found to be 3.41times10^-48 cm⁴.s/photon in PMMA host. The magnitude of third order nonlinear parameters increases when the compound is doped into PMMA matrix because of change in the conformation of chain geometry as a result of charge transfer processes. The values are comparable with a best known nonlinear liquid crystal molecule namely, 4-cyano-4´-n-pentylbiphenyl in the nematic phase. Hence, these molecules can be suitably used as nonlinear optical materials in PMMA matrix for device applications.