Erasure effect of the reading beam on the decay process of chi((2)) in all-optical poling

We have studied the effect of the reading beam on the decay process of the photoinduced second-order susceptibility chi((2)) in both the guest-host sy stem (disperse red I-doped polymethyl methactrylate) and the side-chain sys tem (disperse red 19-functionalized polyimide polymer). Both experimentally and theoretically, we have proved that the reading beam has the erasure ef fect on the decay process, that is, chi((2)) decays faster in the high inte nsity than in the low intensity of the reading be:un. Furthermore, the rela tionship between the time constant re of the slow component of the decay pr ocess and the intensity of the reading beam I-1.06 is derived from the theo retical equations, which is fitted well with the experimental results. Base d on the fitting parameters, we also compare, quantitatively, the thermal-i nduced orientational diffusion of trans- and the quantum efficiency of tran s-to-cis photoisomerization in the two systems.