Photo-induced depoling

Together with PAP, photo-induced depoling (PID) is another interesting phenomenon at the interface of photochemistry and organic nonlinear optics. Indeed, PID of poled polymers occurs when NLO chromophores, which are oriented in a polar manner, undergo photoisomerization without applied dc field. The chromophores lose their initial polar orientation after photoisomerization and reorientation in azimuthal directions around the initial polar axis, thereby erasing FID has been observed both by photo-induced destruction of EO Pockels and by second harmonic generation. The first published PID experiments have been reported for DRl in PMMA, and the theory of PID is discussed in detail in reference 25. 

5 Photo-induced depoling of the DRl-PMMA copol er blended with PMMA wiidi l( w/w DRl-PMMA in PMMA, with p- and s-polarized blue light irradiation 120 mW/cm from a 488 nm Ar laser). The second harmonic probe was s-polarized. The irradiating pump being turned on and off is indicated. Adapted from reference 8, and redrawn by permission of ACS. 

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