Green light direct writing of ferroelectric domains in Mg-doped LiNbO3

So far, visible light-induced domain reversal (LIDOR) in LiNbO3 has only been observed to occur under assistance of an external electric field. Here, we develop a two-step technique to directly achieve green-LIDOR for the first time. In the first step, an external electric field as well as the green laser of 532 nm wavelength is applied on the LiNbO3 crystal. In the second step, direct writing of domain structures in LiNbO3 is realized by another 532 nm laser without assistance of external electric field. Green-LIDOR results from a light-induced space-charge field generated by the prior application on an external electric field in the first step. Due to the unique two-step method, our further experiments show that light-induced space-charge field in LIDOR enhances with increasing the applied external electric field. Therefore, we propose a carrier-drift model to this phenomenon. (C) 2014 Optical Society of America