Intensive studies on fabrication, characterization and performance of second harmonic generation devices on periodically inverted ferroelectric domain lithium tantalate crystals are taking place, but studies on basic material properties of crystals in the domain inversion process are lacking.
Several methods have been applied to obtain the crystals with regular domain structures. The most common is the use of patterned electric field poling, but the quality of resultant periodically poled material can depend on a number of factors and periodicities below ~3 mcm are difficult to produce however, particularly with simultaneously large aspect ratios.
On the other hand all post-growth techniques for achieving periodic domain profiles require either specialist clean-room photolithographic fabrication of patterned electrodes, or lengthy thermal or electron-beam scanning processes. Recently the experiments demonstrating the advantages of direct optical control of ferroelectric domain profiles have been carried out. Here we present our findings and detailed analysis on time dependence of the ferroelectric coercive field after domain inversion of the LiTaO3 and stoichiometric LiNbO3 crystals and report a simple room temperature technique for patterning the domain profile by the simultaneous application of combined electrical and optical fields: the electric field is applied via planar electrodes, while light is used to define those regions where domain inversion should occur. The optical poling route therefore offers a potentially simpler method, effectively eliminating the photolithographic patterning steps.
We have investigated the mechanisms of optical control of domain structures in ferroelectrics, in particularly the roles of the various internal field components, their origins and dynamic behavior following domain reversal. Our experiments have shown the possibility of direct optical control of domain patterning in ferroelectrics.