National Institute for Materials Science

Other

National Institute for Research in Inorganic Materials

Pioneer Corporation

Sumitomo Osaka Cement Co., Ltd.

Shunji Takekawa

Kenji Kitamura

Yasunori Furukawa

Masaru Nakamura

Hideki Hatano

Sunao Kurimura

Myeongkyu Lee

Satoru Tanaka

Takashi Yamaji

Kazuya Terabe

Shigeyuki Kimura

Junichiro Ichikawa

Takashi Fujii

Katsutoshi Kondou

Makoto Kumatoriya

Futoshi Yamamoto

Mikio Geho

Shinichiro Chiku

Xiaoyan Liu

Yoshihisa Ito

Shunichi Hishida

Tamaki Shimura

Shunichi Hishita

A method of fixing a polarization-reversed region formed in a ferroelectric single crystal, including preparing a ferroelectric single crystal having a polarization-reversed region; and irradiating an ion beam or a neutral beam on the ferroelectric single crystal. The ferroelectric single crystal is a substantially stoichiometric lithium tantalate single crystal or a substantially stoichiometric lithium niobate single crystal, and the polarization-reversed region is fixed and any back switch and expansion of the polarization-reversed region are suppressed.

Method of fixing polarization-reversed region formed in ferroelectric single crystal

An optical material includes lithium tantalate, and a molar composition ratio of lithium oxide and tantalum oxide (LiO/TaO) in the lithium tantalate is in the range of 0.975 to 0.982. Since an optical material having a high refractive index is provided in an optical unit, at the same focal distance, a lens thickness can be significantly reduced. As a result, an optical electronic component and an optical electronic device including the optical material has a reduced size and thickness and is highly functional.

Lens material, optical electronic component and optical electronic device

An optical device and a method of manufacturing the optical device, with the method including the steps of forming a dopant layer on a stoichiometric lithium niobate single crystal substrate with Li to Nb mole composition ratio of 49.5% to 50.5%, and diffusing a dopant in the dopant layer into at least a portion of the stoichiometric lithium niobate single crystal substrate. The stoichiometric lithium niobate single crystal substrate includes 0.5 to 5 mol % of Mg. In the diffusing step, a heat treatment is performed at a diffusion temperature of 1000&#xb0; C. to 1200&#xb0; C. for a diffusion time of 3 hours to 24 hours in a dry atmosphere of at least one of O, N, Ar and He gas having a dew-point temperature of &#x2212;35&#xb0; C. or less.

Optical device and method of manufacturing the same

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 Dthan the defect density Dof a ferroelectric single crystal (D&#x3c;D) or forming (ii) a control layer having a lower degree of order of lattice points than the degree of order of lattice points of the ferroelectric single crystal on a face perpendicular to the direction of polarization of the ferroelectric single crystal in the ferroelectric single crystal.

Method of inverting polarization by controlling defect density or degree of order of lattice points

A wavelength conversion element having multi-gratings free from damage propagation and a light generating apparatus using it, and a wavelength conversion element having multi-gratings to make a thermal distribution centrosymmetric, and being free from damage propagation, are provided. The wavelength conversion element is realized by comprising a holder and plural prismatic ferroelectric single crystals disposed in the holder, wherein plural prismatic ferroelectric single crystals have at least five planes; the aspect ratios of planes perpendicular to respective longitudinal directions of the plural prismatic ferroelectric single crystals are virtually unity; and each of the plural prismatic ferroelectric single crystals has a domain inversion structure with a predetermined period in the direction perpendicular to the polarization direction thereof, and is arranged in a way that said direction perpendicular to the polarization direction is the same as those of the other crystals.

Wavelength conversion element having multi-gratings and light generating apparatus using said element, and wavelength conversion element having cylindrical ferroelectric single crystals and light generating apparatus using said element

A holographic recording medium exhibiting a high recording sensitivity without execution of reduction treatment. A system records information on the holographic recording medium by using a gating light within a wavelength band causing less optical damage to the holographic recording medium. The holographic recording medium includes a single crystal of lithium niobate (LiNbO) or lithium tantalate (LiTaO) containing Mn as a dopant.

Holographic recording medium and holographic recording/reproducing apparatus using the same

A method for treating a photorefractive effect of an optical device, which comprises irradiating an optical device comprising a lithium niobate single crystal or a lithium tantalate single crystal with an ultraviolet light having a wavelength of at least 300 nm and at most 400 nm so as to suppress and control a photo-induced refractive index change (photorefractive effect) caused on the device.

Method for treating photorefractive effect of an optical device and photorefractive effect-suppressed optical frequency conversion device

An optically functional device comprising a ferroelectric single crystal substrate and polarization-inverted structures formed at portions of the substrate at a temperature of not higher than the Curie temperature by an electron beam scanning irradiation method or a voltage application method and designed to control light passed through the polarization-inverted portions, wherein a LiNbO crystal having a molar ratio of Li/Nb within a range of from 0.95 to 1.01, is used as the substrate, so that the propagation loss of light passed through the polarization-inverted portions immediately after formation of the polarization-inverted structures, is not more than 2%.

Optically functional device, single crystal substrate for the device and method for its use

A single crystal of lithium niobate or lithium tantalate may be grown from a melt of a composition having a molar excess of Li compared to a melt having the stoichiometric amount of lithium, and having a molar fraction of Li O/(Nb O &plus;Li O) or Li O/(Ta O &plus;Li O) within a range of at least 0.490 and less than 0.500. The single crystal also has at least one element selected from the group consisting of Mg, Zn, Sc and In, in an amount of from 0.1 to 3.0 mol % based on the total amount of the elements, Nb and Li, or the total amount of the elements, Ta and Li.

Single crystal of lithium niobate or tantalate and its optical element, and process and apparatus for producing an oxide single crystal

A photorefractive material provides a high photosensitivity without reduction. The material comprises a single crystal of terbium (Tb)-doped niobate or tantalate. The single crystal is a single crystal of lithium niobate (LiNbO ) whose molar fraction of &lsqb;Li O&rsqb;/(&lsqb;Li O&rsqb;&plus;&lsqb;Nb O &rsqb;) lies in a range of 0.482 to 0.505, or a single crystal of lithium tantalate (LiTaO ) whose molar fraction of &lsqb;Li O&rsqb;/(&lsqb;Li O&rsqb;&plus;&lsqb;Ta O &rsqb;) lies in a range of 0.482 to 0.505. The amount of terbium added in the photorefractive material ranges from 10 weight ppm to 1000 weight ppm.

Photorefractive material

An optically functional device comprising a ferroelectric single crystal substrate and polarization-inverted structures formed at portions of the substrate at a temperature of not higher than the Curie temperature by an electron beam scanning irradiation method or a voltage application method and designed to control light passed through the polarization-inverted portions, wherein a LiTaO crystal having a molar ratio of Li/Ta within a range of from 0.95 to 1.02, is used as the substrate, so that the propagation loss of light passed through the polarization-inverted portions immediately after formation of the polarization-inverted structures, is not more than 2%.

A hologram recording apparatus is capable of directing interferable signal light and reference light into a hologram recording medium to record an information signal carried by the signal light. The hologram recording medium is sensitive to a first light at a first wavelength in an ultraviolet or short-wavelength visible light band to develop light induced absorption. The apparatus includes a light source for irradiating the hologram recording medium with the first light, and a laser light source for irradiating the hologram recording medium with signal light and reference light at a second wavelength longer than the first wavelength after the first light is irradiated.

Hologram recording apparatus and method therefor

A two-color holographic recording apparatus reduces error signals possibly included in reproduced digital data signals. The two-color holographic recording apparatus has first, second and third light shutters for passing or blocking gate light, signal light and reference light incident on a recording medium respectively, and a controller for controlling the respective states of the first, second and third light shutters.

Two-color holographic recording apparatus

A stoichiometric single crystal of lithium niobate or lithium tantalate is produced by pulling a single crystal of lithium niobate or lithium tantalate having a molar fraction of Li O/(Nb O &plus;Li O) or Li O/ (Ta O &plus;Li O) of at least 0.490 and less than 0.500, from a melt of a composition having a molar excess of Li over a stoichiometric composition of lithium niobate or lithium tantalate. The single crystal has 0.1 to 3 mol % of at least one element selected from the group consisting of Mg, Zn, Sc and In based on a total amount of elements Nb and Li, or a total amount of elements Ta and Li. The single crystal has substantially no absorption in the visible light region.

A two-color hologram recording/reproducing apparatus is capable of directing interferable signal light and reference light into a hologram recording medium to record an information signal carried by the signal light. The hologram recording medium is sensitive to a first light at a first wavelength in an ultraviolet or short-wavelength visible light band to develop light induced absorption. The apparatus includes a light source for irradiating the hologram recording medium with the first light, a laser light source for irradiating the hologram recording medium with signal light and reference light at a second wavelength longer than the first wavelength after the first light is irradiated, and a gate light source for directing gate light at a third wavelength into the hologram recording medium. The gate light causes the hologram recording medium to develop a recording sensitivity to activate or inactivate a refractive index grating in accordance with existence or non-existence of a light interference pattern formed by the signal light and the reference light.

Growing community of inventors

Tsukuba, Japan

Shunji Takekawa