Direct laser poling of lithium niobate on insulator with femtosecond laser

We demonstrated experimentally direct femtosecond writing of ferroelectric domains in lithium niobate on insulator. The fabricated ferroelectric domain structures were characterized using Cherenkov second harmonic microscopy and piezoresponse force microscopy. We also experimentally explored the far-field second harmonic generation from the laser-induced ferroelectric domain structures. This study opens the door for direct laser writing of lithium niobate-based integrated photonic circuits, which typically require on-chip frequency conversion and wavefront control.