Hitachi, Ltd.

Other

Atsuko Fukushima

Kenchi Ito

Yasuo Hira

Kazumi Kawamoto

Hidemi Sato

Masataka Shiba

Ryuichi Funatsu

Akira Inagaki

Minoru Yoshida

Akira Arimoto

Naoya Kanda

Hiroshi Asao

Hiroshi Momiji

A second harmonic generator having a wide acceptance of bandwidth of temperature and/or a high conversion efficiency and a method of fabrication thereof are disclosed. An equidistant arrangement of pole-inverted grating having a rectangular sectional profile and the direction of spontaneous polarization opposite to that of a substrate within an optical waveguide has been known to produce a high conversion efficiency of the second harmonic generator A second harmonic generator having such a structure, which has so far been impossible to fabricate, is formed utilizing the liquid-phase epitaxial method and the ion-implanting method. Further, the substrate and the optical waveguide are formed of the same type of material. The temperature coefficient of the refractive index in the direction perpendicular to the substrate surface is rendered substantially equal to that of the optical waveguide, thereby improving the acceptance of bandwidth of temperature and making possible practical applications of the second harmonic generator.

Second harmonic generator and method of fabrication thereof

Using an optical pickup, recording/reproducing of information is performed by irradiating light beams to an optical recording medium to form light spots. The optical pickup includes means for generating plural light beams, an optical waveguide for guiding the plural light beams in a row into a flat space, and a light deflecting element for deflecting the light beams, which run in the optical waveguide, within a plane formed by a vector perpendicular to a plane of the optical waveguide and a directional vector of the light beams. The light deflecting element deflects the plural light spots, which are to be arranged in a row, in a direction perpendicular to the light spot row to perform micro seek.

Optical information processing apparatus and optical pickup therefor

An optical waveguide is comprised of an optical substrate and an optical thin-film optical waveguide layer and formed such that ##EQU1## where .theta. is an output angle, n.sub.o1 is an ordinary refractive index of the optical substrate for an ordinary beam, n.sub.e1 is an extraordinary refractive index of the optical substrate for an extraordinary beam, n.sub.o2 is an ordinary refractive index of the optical thin-film optical waveguide layer for the ordinary beam and n.sub.e2 is an extraordinary refractive index of the optical thin-film optical waveguide layer for the extraordinary beam, and an electrode for generating a surface acoustic wave for diffracting light is formed on the optical waveguide to construct a collinear optical deflector. A method for production of the optical thin-film optical waveguide layer is exemplified wherein a target made of tantalic lilthium niobate or tantalic lithium niobate magnesium and an optical substrate made of lithium tantalate are prepared and an optical thin-film optical waveguide layer having a composition of tantalic lithium niobate or tantalic lithium niobate magnesium is formed on the optical substrate through an ion beam sputtering process into which oxygen can be introduced. Proton substitutes for part of an element constituting the optical thin-film optical waveguide layer.

Optical information storing apparatus and method for production of

A sample is located so as to be close to a prism and a light beam coming from a light source is projected to the prism while varying the incident angle to the prism as a parameter. The incident light beam to the prism is propagated therein and light emerging from the bottom surface of the prism, which is in contact with the sample, is projected to the sample. At the same time the intensity of light reflected by the bottom surface of the prism is measured. Optical constants such as the refractive index, the film thickness, the distribution of the refractive index, etc. are obtained by calculation, starting from measured values thus obtained.

Method and apparatus for measuring optical constants of a thin film as

An optical integrated circuit and an optical apparatus used in optical communication or an opto-electronics apparatus such as an optical disk recording apparatus, in which various kinds of aberration caused by wavelength variation of a light source when a semiconductor laser is used as the light source. An aberration correcting grating having such grating pitches as to nearly satisfy the Bragg condition preferably with respect to a certain wavelength of the semiconductor laser beam is used. As a result, lowering of incidence (entrance) and radiation (exit) coupling efficiencies of the grating coupler and aberration such as chromatic aberration can be prevented. Even if a multi-mode semiconductor laser is used as a light source, the characteristics of the optical integrated circuit and optical apparatus do not vary largely.

Optical integrated circuit and optical apparatus

Growing community of inventors

Yokohama, Japan

Atsuko Fukushima