Polarization inversion method of ferroelectrics and fabrication method of optical wavelength conversion device

1. Field of the Invention A method for forming a polarization inversion portion, in which electrodes with a predetermined pattern are formed on one surface of a ferroelectric crystal that has been subjected to a single polarization, and a local polarization inversion portion corresponding to the pattern of the electrodes is formed in the ferroelectric crystal by applying electric field to both front and back surfaces of the ferroelectric crystal via the electrodes, makes it possible to accurately form a polarization inversion pattern. In this method, portions of the ferroelectric crystal corresponding to the respective electrodes and portions between these portions are subjected to a polarization inversion, and one polarization inversion portion is formed.