Hitachi Metals, Ltd.

Hitachi, Ltd.

Fumio Nitanda

Ryo Goto

Kohei Ito

Makoto Ushijima

Manabu Toyoda

Tadafumi Tomitani

Kenchi Ito

Shinji Furuichi

Masayoshi Sato

Satoshi Makio

Masanobu Yamazaki

Kimio Tatsuno

Tetsuo Andou

Kazumi Kawamoto

Osamu Komoda

Masahiro Ao

Yasunori Furukawa

Hisao Kurosawa

Yoshiaki Uchida

Hiroshi Momiji

Sten Helmfrid

Kazutami Kawamoto

Tomoki Soutome

Masazumi Sato

Yasuhiro Furukawa

An optical switching device comprising a plurality of mechanical optical switching structures having one to several movable optical fibers and one to several fixed optical fibers installed in a housing in which a refractive index matching oil is filled up and immerses the structures. Each of the structures has an electromagnetic actuator to reciprocate open ends of the movable optical fibers relatively to open ends of the fixed optical fibers and to connect/disconnect optical paths. Ends opposite to the open ends of the movable optical fibers and the fixed optical fibers are drawn out through ports located on the housing so that a certain number of optical fibers among the optical fibers drawn out serve as input optical fibers, while a certain number of optical fibers among the other optical fibers drawn out serve as output optical fibers, to constitute the optical switching device of m&#xd7;n type, in which m is the number of input paths and n is the number of output paths, providing a small-sized optical switching device having variable numbers of input/output paths.

Optical switching device comprising plural mechanical optical switches

An optical switch comprising a fixed optical-fiber holder for holding either of input/output optical fibers, a movable optical-fiber holder for holding the other of the input/output optical fibers, which faces the fixed optical-fiber holder and is movable with respect to the fixed optical-fiber holder, and a driver for moving the movable optical-fiber holder with respect to the fixed optical-fiber holder immersed in the refractive index matching material, such as silicone oil. Inside the housing provided are a heater for heating the refractive index matching material, a means for sensing temperature inside the housing, and a controller for turning on the power to the heater when the measured value of the temperature sensing means is lower than a first predetermined value, and turning off the power to the heater when the measured value of the temperature sensing means is higher than a second predetermined value. This optical switch is capable of maintaining proper operation even when its service temperature becomes low, and preventing overheat.

Optical switch

There is disclosed a harmonic modulation device of waveguide type including a semiconductor laser, a waveguide for generating a nonlinear optical harmonic of the semiconductor laser by keeping phase matching, means for leading an optical beam of the semiconductor laser to the waveguide, electrodes disposed on the waveguide, and means for modulating a refractive index of the waveguide electro-optically to modulate a phase matching condition and thereby modulate an intensity of the harmonic.

Short-wavelength laser light source

Two floating rails are provided on a slider of a floating magnetic head. Rear portions, in the advancing direction of a floating magnetic head with respect to a magnetic recording medium, of the respective floating rails are cut out. That is, the floating rails exist only in front of the cut-out portions. An auxiliary rail is formed in the rear of one of the floating rails. The auxiliary rail is narrower than the floating rail, wider than the track width of an electromagnetic conversion element, and approximately as high as the floating rail. The electromagnetic conversion element is provided at a rear portion of the auxiliary rail.

Floating magnetic head

Using an LiTaO.sub.3 or LiNbO.sub.3 substrate, a proton exchange layer in a grid pattern, namely sprout areas of polarization inversion, is firstly, formed on the surface of said substrate and, after formation of the pattern, heat treatment is executed at a temperature of 200.degree. C. or more and for a holding time of 10 minutes or less. By maintaining the temperature gradient up to said heat treatment point at 50.degree. C./min. or steeper and by maintaining the temperature decrease rate from said heat treatment point at 50.degree. C./min. or faster, polarization inverted areas are formed downwards from the proton exchanged areas, while in addition to making the top ends of said polarization inverted areas into an acute angle, the depth/weight ratio of the polarization inverted grids being formed is made to exceed 1, thus enabling the production of a high-efficiency SHG element.

Second harmonic generating element and the production method thereof

0.1% or more of Mg by weight is added to lithium tantalate monocrystal materials wherein the amount of Fe is restricted to 10 ppm by weight or less to improve light transmittance in the short wavelength range of blue light and to shift the fundamental absorption edge to the shorter wavelength.

Lithium tantalate monocrystal, monocrystal substrate, and photo element

A flying-type composite magnetic head includes (a) a magnetic core constituted by a pair of core pieces bonded together by a first glass portion, at least one of opposing surfaces of the core pieces being formed with a thin magnetic metal layer; (b) a non-magnetic slider having a slit for receiving the magnetic core; and (c) a second glass portion for fixing the magnetic core in the slit; the first glass portion having a softening point lower than a first bonding temperature by 70.degree. C. or more and a yielding temperature higher than a second bonding temperature, and the second glass portion having a softening point lower than a second bonding temperature by 70.degree. C. or more. The first bonding temperature T.sub.1 (.degree.C.) for forming the first glass portion satisfies the following relation:

Method of producing a fly-type composite magnetic head with appropriate

A flying-type composite magnetic head includes (a) a magnetic core constituted by a pair of core pieces bonded together by a first glass portion, at least one of opposing surfaces of the core pieces being formed with a thin magnetic metal layer; (b) a non-magnetic slider having a slit for receiving the magnetic core; and (c) a second glass portion for fixing the magnetic core in the slit; the first glass portion having a softening point lower than a first bonding temperature by 70.degree. C. or more and a yielding temperature higher than a second bonding temperature, and the second glass portion having a softening point lower than a second bonding temperature by 70.degree. C. or more. The first bonding temperature T.sub.1 .degree.C.) for forming the first glass portion satisfies the following relation:

Flying-type composite magnetic head with appropriate bonding glasses and

A magnetic core for a flying-type composite magnetic head, including a pair of core pieces, a glass portion for bonding the core pieces, and a thin magnetic metal layer of Fe-Al-Si alloys formed on at least one of opposing surfaces of the core pieces. The thin magnetic metal layer extends by 10 .mu.m or more from an apex of a magnetic gap defined by the core pieces and has an inner end existing by 15 .mu.m or more inside an inner end of the bonding glass portion.

Magnetic core for flying-type composite magnetic head

Growing community of inventors

Fukaya, Japan

Fumio Nitanda