Apparatus for the fabrication of periodically poled frequency doubling crystals

摘要

A laser heated pedestal growth system for growing a periodically poled, single crystal rod having domain interfaces substantially parallel to the rod's long axis. Suitable crystalline ferroelectric feed materials have a Curie temperature no greater than ˜200° C. below its melting point and include Lithium Niobate and MgO doped Lithium Niobate. The system comprises:;i) a laser that generates first and second laser beams;ii) the first laser beam being a molten zone beam for melting the feed material and the second being an afterheater beam;iii) two spaced apart wire electrodes situated on either side of the crystal rod parallel to the growth direction of the crystal rod, and connected to an alternating electrical current source which creates an electric field between the electrodes which is parallel then anti-parallel to the crystal rod growth axis;iv) an Infra-Red scanner and computer controlled feedback system for controlling the axial and radial temperature gradients in the crystal rod in the region between the electrodes.