Direct-write e-beam sub-micron domain engineering in liquid phase epitaxy (LPE) LiNbO3 thin films and single crystal LiNbO3

We have demonstrated sub-micron domain (∼200 nm) structures with a period ∼750 nm and ∼1.2 μm in liquid phase epitaxy (LPE) LiNbO3 films on congruent LiNbO3 substrates by using the direct-write e-beam domain engineering method. In comparison with single crystal congruent LiNbO3 (CLN) and stoichiometric LiNbO3 (SLN), we show that LPE LiNbO3 (LPE LN) is the most promising material for producing superior domain regularities and finer domain sizes than single crystals. A physical model is presented to qualitatively explain the observed differences in structure and regularity of the induced periodic domains among the three different materials we studied. We postulate that the higher Li/Nb ratio in LPE LN than in CLN enhances domain inversion initiation. Also, we believe that the vanadium incorporation and distortion due to the lattice mismatch between films and substrates enhance electron localization, domain wall pinning and domain nucleation in LPE materials, giving rise to better structures.