Embryonic nucleation method for fabrication of uniform periodically poled structures in potassium niobate for wavelength conversion devices

A new electric poling concept called the 'embryonic nucleation method' for the fabrication of periodically poled structures has been proposed. By applying this method to KNbO3, 1-mm-thick uniform periodically poled KNbO3 (PPKN) with domain inverted period of 35.5 mum and an interaction length of 10 mm has been successfully fabricated by applying only 300 V/mm without the generation of unwanted domains. Furthermore, the reproducibility of the periodic poling process has been greatly improved. SHG using PPKN fabricated by this method was demonstrated and 100 mW second-harmonic laser generation at a wavelength of 532 nm was obtained from 1 W pumping without photorefractive damage at approximately 40degreesC.