| 摘要 |
<p>PROBLEM TO BE SOLVED: To form uniformly a deep and short-periodic polarization inversion region over a large area of a substrate for the manufacture of an optical wavelength conversion element of a short wavelength and a high efficiency. SOLUTION: A comb-shaped electrode 2 and a planar electrode 3 are formed on the front and the back surfaces of a substrate 1, respectively. To these electrodes, a DC voltage, on which a pulse voltage is superposed is applied by using a DC supply 4 and a pulse supply 5 so that a DC electric field, on which a pulse electric field is superposed, is applied to the substrate. Thereby, a periodic polarization inversion region can be formed by applying a small pulse electric field. Since the uniformity of the applied electric field on the surface of the substrate is high, to form a polarization inversion region with a uniform periodic structure is formed. Alternatively, after covering the comb-shaped electrode with a insulating film, a pulse electric field is applied to the substrate by applying a pulse voltage to the electrode from the pulse supply, which restricts the movement of free electrons on the surface of the crystal and suppresses the expansion of the polarization inversion in the lateral direction and results in the formation of an uniform and short period polarization inversion structure.</p> |
