IMPROVED NLO PROPERTIES THROUGH A LIQUID-CRYSTAL PHASE POLING

Cross-linkable organic NLO chromophore called DRS was chemically incor porated into silica matrices using the sol - gel process. A number of electrically poled DRS/silica matrix systems were studied to elucidate the relaxation of the oriented organic chromophore by following the d ecay of UV absorption as a function of time and temperatures. The valu e of the second harmonic coefficient d(33) was 47pm/V for the DRS/sili ca matrix films (0.4 mu m thickness). From the dramatic decrease in th e UV absorption after poling at 80 degrees C, it is speculated that th e DRS may act as a liquid crystalline mesogenic group and is effective ly oriented in poling at the phase (nematic) transition temperature (8 0 degrees C). This argument was substantiated by investigating the pha se behavior of Das itself using both DSC and a polarized optical micro scope. The DRS/silica system contained the ideal matrices to retain th e oriented chromophore because of optical clarity, thermal stability a nd effective poling at the nematic liquid crystalline phase.