Patent ID: 7230753

Claim:
A method for forming a domain-inverted structure comprising: using a ferroelectric substrate having a principal surface substantially perpendicular to a Z axis of crystals of the ferroelectric substrate; providing a first electrode on the principal surface of the ferroelectric substrate, the first electrode having a pattern of a plurality of electrode fingers that are arranged periodically; providing a counter electrode on the other side of the ferroelectric substrate so as to be opposite from the first electrode; and applying an electric field to the ferroelectric substrate with the first electrode and the counter electrode, thereby forming domain-inverted regions corresponding to the pattern of the first electrode in the ferroelectric substrate, wherein each of the electrode fingers of the first electrode is located so that a direction from a base to a tip of the electrode finger is aligned with a Y-axis direction of the crystals of the ferroelectric substrate, and the electric field is applied to the ferroelectric substrate so that a mean value of a depth D of the domain-inverted regions is 40% to 95% of the thickness of the ferroelectric substrate.