We investigate the characteristics of the poling process of two samples of Er : LiNbO ₃ grown by the Chzocralski technique by comparing their optical properties. The first has a multidomain structure and shows some optical inhomogeneities probably due to lattice defects; the second, poled at the high temperature just after the growth, has a ferroelectric monodomain structure. Moreover, in order to highlight the effect of the high temperature poling, a further poling process was performed on both the samples at room temperature and was monitored in real time through a simple optical setup in order to evidence whether the erbium inclusion influences the poling process and which are the differences between the poling dynamics of the two samples. The results show that the erbium causes a change of the coercive field value with respect to the pure congruent LiNbO ₃ crystals, and that the multidomain structure influences strongly the poling dynamics.