An improvement on the simplified theory of all-optical poling [Chem. Phys. Lett. <b>286,</b> 415 (1998)] is proposed. In this improvement the influence of the <i>cis</i> isomer is taken into account in the process of photoinduced molecular polar alignment. An analytical expression for the induced polar order in the steady-state regime is derived. This expression shows that, although the contribution to the photoinduced second-order susceptibility from the <i>cis</i> state itself can be neglected, the population of the <i>cis</i> state plays an important role. This result suggests the possibility that one can improve the induced polar order by increasing the poling temperature, so that thermal-assisted optical poling can be explained.
© 2000 Optical Society of America
Gang Xu, Xuchun Liu, Jinhai Si, Peixian Ye, Zhao Li, and Yuquan Shen, "Modified theory of photoinduced molecular polar alignment in azo polymers," Opt. Lett. 25, 329-331 (2000)