Other

Myeongkyu Lee

Kenji Kitamura

Hideki Hatano

Shunji Takekawa

Yasunori Furukawa

Satoru Tanaka

Takashi Yamaji

Yoshihisa Ito

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

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 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

Myeongkyu Lee