Improved NLO properties through a liquid crystal phase poling

Cross-linkable organic NLO chromophore called DRS was chemically incorporated 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 decay of UV absorption as a function of time and temperatures. The value of the second harmonic coefficient d(33) was 47pm/V for the DRS/silica matrix films (0.4 mu m thickness). From the dramatic decrease in the UV absorption after poling at 80 degrees C, it is speculated that the DRS may act as a liquid crystalline mesogenic group and is effectively oriented in poling at the phase (nematic) transition temperature (80 degrees C). This argument was substantiated by investigating the phase behavior of Das itself using both DSC and a polarized optical microscope. The DRS/silica system contained the ideal matrices to retain the oriented chromophore because of optical clarity, thermal stability and effective poling at the nematic liquid crystalline phase.