Retardation of orientation relaxation of azo-dye doped amorphous polymers upon all-optical poling

The orientation relaxation of azo-dyes upon all-optical poling was studied. Azo-dye doped amorphous polymers were poled for different durations by all-optical poling at several temperatures. A quasi-permanent macroscopic second-order nonlinear optical susceptibility χ(2) was inscribed in the dye-doped centrosymmetric polymer systems. Relaxation of the χ(2) was monitored by second harmonic generation. It shows that the polar orientation relaxation follows the duration of the poling process: the longer the poling, the slower the polar relaxation time. Causes of the orientation relaxation retardation are discussed.