Abstract:
PROBLEM TO BE SOLVED: To provide a mean for surely manufacturing a single crystal having a large diameter and free from inclusions. SOLUTION: A lithium niobate single crystal or lithium tantalate single crystal having a large diameter and free from inclusions such as air bubbles is obtained by applying an accelerated crucible rotation technique (ACRT) comprising changing the rotation number or the rotation direction of a crucible to a single crystal growth technique based on a double crucible method, and thereby, controlling the movement of the crucible and enhancing the agitation effect. COPYRIGHT: (C)2003,JPO
Abstract:
PROBLEM TO BE SOLVED: To highly precisely and uniformly form a polarization inversion struc ture without any optical distortion. SOLUTION: The optical functional element is obtained by forming the polarization inversion structure at the temperature lower than the Curie temperature by using an electron beam scanning irradiation method or voltage application method in a part of a ferroelectric single crystal substrate preparedly using LiNbO3 crystal having 0.95 to 1.01 molar ratio of Li/Nb as the substrate, and the optical functional element controls the light passing through the polarization inversion part. By this method,
Abstract:
PROBLEM TO BE SOLVED: To provide a high-efficiency structure of an optical wavelength converting element in which inhomogeneity in the polarization inversion structure due to processes of forming an optical waveguide is prevented by repeating part of the periodical polarization inversion structure formed in a stoichiometric LN crystal to stabilize the structure. SOLUTION: The optical wavelength converting element has a stoichiometric LiNbO3 crystal substrate 1 having 49.5 to 50.2% molar ratio of Li2O/(Nb2O5+Li2 O) and a polarization inversion part 2 formed on the surface of the crystal. The polarization inversion part 2 is periodically arranged, at least part of which being formed in contact with each other by repetition. A comb-like electrode is formed on the surface of the substrate 1, a flat electrode is formed on the back face of the substrate and a voltage is applied between the electrodes to grow the polarization inversion from the comb-like electrode. The polarization inversed part and its continuous part are formed inward in the crystal. Then a proton exchange optical waveguide 3 is formed by proton exchanging and annealing.
Abstract:
PROBLEM TO BE SOLVED: To uniformly form a polarization inversion structure free of optical distortion with good accuracy. SOLUTION: This optical function element is constituted by forming the polarization inversion structure at a temperature below a Curie temperature in part of a ferroelectric single crystal substrate formed by using an LiTaO3 crystal ranging from 0.95 to 1.02 in the molar ratio of Li/Ta as a substrate by using an electron beam scanning irradiation method or voltage impression method and controlling the light past this polarization inversion structure. Propagation loss of
Abstract:
PROBLEM TO BE SOLVED: To provide a crucible and an apparatus for producing a single crystal, capable of independently controlling the temperatures of a melting tank and a growing tank and realizing the temperature distribution at the inside of the growing tank, providing a heat convection ideal for a pulling method and with which a large scale single crystal having a uniform composition and a prescribed target diameter can be produced, and to provide a method of producing the same using the same. SOLUTION: In the crucible for producing the single crystal, the melting tank is connected to the outside, from the middle of the side wall of the growing tank and communicatable flow holes are formed in the sidewall of the growing tank so that molten liquid can flow in or out between the inside of the melting tank and the inside of the growing tank. The single crystal can be obtained by supplying a powdery raw material into the melting tank of the crucible, mentioned above, for producing the single crystal, then melting the raw material, dipping a seed crystal into a melt flowing-in from the melting tank and pulling up the single crystal while growing the single crystal.
Abstract:
An optical material that is not affected by environmental changes, exhibiting a birefringence falling within the range of ±0.0005; and an optoelectronic part and optoelectronic appliance including the optical material. There is provided an optical material of lithium tantalate characterized in that in the lithium tantalate the molar composition ratio of lithium oxide to tantalum oxide (LiO2/Ta2O5) is in the range of 0.975 to 0.982. Since an optical material of high refractive index can be used in an optical system, the lens thickness can be reduced at an unchanged focal length. As a result, by the use of lens with such characteristics, not only can optoelectronic parts having realized higher levels of compactness, thin model and function enhancement be provided but also optoelectronic appliances having these characteristics can be presented.
Abstract:
There is provided a method for forming a short-cycle polarization inverting region in a ferroelectric single crystal within a controllable voltage application time. A light wavelength conversion element using the method is also provided. The aforementioned is achieved by (i) forming a control layer having a defect density Dcontl greater than the defect density Dferro of the ferroelectric single crystal (Dferro
Abstract:
A problem to be solved is to provide a method of forming domain inverted regions of short period in a ferroelectric single crystal in a controllable time period of application of voltage and an optical wavelength conversion element using the same. A solving means of it solves the problem by forming (i) a control layer having a larger defect density D cont1 than the defect density D ferro of a ferroelectric single crystal (D ferro