Abstract: A crystal poling apparatus has as ingle-domain ferroelectric substrate (e.g. MgO doped LiNbO3 substrate), a sample holder, a high voltage source, a corona torch, a gas source, a chamber, and at least one vacuum pump. An electrode with a certain structure (e.g. a periodical pattern) is formed on the first surface of the substrate, and the substrate is set with the electrode facing down on top of the sample holder. The electrode is grounded so that high electric field is formed in the area with electrode due to the formation of charges generated by the corona torch on the second surface of the substrate. The charge distribution on the second surface of the substrate is controlled by the high voltage source and the gas source. To achieve the optimized crystal poling, the temperature of the substrate is set by the temperature controller, and the electrode on the first surface of the substrate is isolated by the vacuum pump.