Experimental observation of electric-field poling in femtosecond laser carved LiNbO3 crystal

We report a preliminary experiment result of poling in a femtosecond-laser-treated LiNbO3 (LN) crystal. Because of the precision of the femtosecond laser machine, we can control the width and depth of snicks exactly. Then the high-voltage electric field was operated on +z side of the LN crystal. The visible poling pattern was observed by it microscope and machining parameter influences the electric field distribution in the crystal. This approach does not need expensive masks and the periods of PPLN can be adjusted flexibly. Although the mechanism of core formation is not very clear yet, we believe that it would provide a novel technique of making prototype PPLN and other periodically poled crystals.