Patents by Inventor Hiroyoshi Matsumura
Hiroyoshi Matsumura has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).
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Patent number: 4737003Abstract: An optical switch wherein a stripe layer of a compound semiconductor whose refractive index is changed by changing a carrier concentration thereof is disposed so as to cut off both optical waveguides at a position of a longer diagonal line of an intersection portion between the optical waveguides formed on a substrate of a compound semiconductor and intersecting each other at a predetermined angle, and the refractive index is changed by causing current to flow to the stripe layer.Type: GrantFiled: December 21, 1984Date of Patent: April 12, 1988Assignee: Hitachi, Ltd.Inventors: Hiroyoshi Matsumura, Naoki Chinone, Koji Ishida
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Patent number: 4737015Abstract: An optical waveguide comprising a layer formed on a substrate, having a mixed composition of silicon oxide and silicon nitride and having an arbitrary value of refractive index ranging between those of the silicon oxide and the silicon nitride. The layer of said mixed composition can be formed on the substrate to easily fabricate the optical waveguide of the present invention by conducting a sputtering method employing a Si target and controlling the composition of a sputtering gas composed of a mixture of N.sub.2 and O.sub.2 gases.Type: GrantFiled: November 26, 1984Date of Patent: April 12, 1988Assignee: Hitachi, Ltd. Hitachi CabelInventors: Koji Ishida, Hiroyoshi Matsumura, Kenji Hiruma, Kazuyuki Nagatsuma, Akihito Hongo
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Patent number: 4730896Abstract: A member capable of transmitting infrared rays of 2 .mu.m or longer in wavelength, particularly of 10.6 .mu.m in wavelength, with a slight loss is provided. The member comprises a Ge-Se-Te ternary chalcogenide glass having a composition which, in a compositional diagram of the ternary chalcogenide glass falls within the region bounded by the respective straight lines connecting points A, B, C, D, and E and A in this order, which points A, B, C, D, and E indicate Ge:Se:Te molar proportions of 32:25:43, 20:6:74, 15:5:80, 15:10:75, and 22:31:47, respectively.Type: GrantFiled: November 20, 1985Date of Patent: March 15, 1988Assignees: Hitachi, Ltd., Hitachi Cable Ltd.Inventors: Toshio Katsuyama, Hiroyoshi Matsumura
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Patent number: 4720836Abstract: The present invention relates to a semiconductor laser which oscillates in a single longitudinal mode and with a low threshold current and which exhibits a good mode stability against reflected light, and provides a structure of a distributed feedback semiconductor laser with modulation for a gain. The structure is such that gain producing regions are periodically arranged and that a substance transparent to laser radiation is buried between the regions. A layer including the gain regions is formed of a superlattice layer, and an impurity is diffused or implanted into periodic positions of the layer, whereby the transparent regions and the gain regions with little lattice damages can be readily formed.Type: GrantFiled: August 20, 1985Date of Patent: January 19, 1988Assignee: Hitachi, Ltd.Inventors: Tadashi Fukuzawa, Hiroyoshi Matsumura, Shinji Tsuji, Hitoshi Nakamura, Kenji Hiruma
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Patent number: 4693543Abstract: The present invention relates to an improvement in the optical transmission characteristics of a ridged type of optical waveguide in an optical integrated circuit. The invention is directed to reducing the effects of irregularities in the ridge sides on the optical transmission losses of the optical waveguide. According to the present invention, therefore, a hardened film of a heat-resistant, high-molecular resin is applied over the ridges and the optical waveguide, greatly reducing the optical transmission losses in the optical waveguide. An appropriate thickness of the heat-resistant, high-molecular resin film is between 200 to 1,000 nm, in consideration of the electric and magnetic fields applied thereto for the operation of the circuit. The present invention makes it possible to provide an optical integrated circuit with an optical waveguide which has low optical transmission losses.Type: GrantFiled: March 7, 1985Date of Patent: September 15, 1987Assignee: Hitachi, Ltd.Inventors: Hiroyoshi Matsumura, Koji Ishida
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Patent number: 4631402Abstract: An apparatus for measuring electric field by making use of electrooptic effect includes an electrooptical crystal having a crystallographically eulytite structure such as Bi.sub.4 Ge.sub.3 O.sub.12, Bi.sub.4 Si.sub.3 O.sub.12 or Bi.sub.4 (Ge, Si).sub.3 O.sub.12 as a material with electrooptic effect. The optical electric-field measuring apparatus has an increased measuring sensitivity and a stabilized temperature characteristic and scarcely disturbs the distribution of electric field to be measured.Type: GrantFiled: February 1, 1984Date of Patent: December 23, 1986Assignees: Hitachi, Ltd., Hitachi Cable, Ltd.Inventors: Kazuyuki Nagatsuma, Kazumasa Takagi, Hiroyoshi Matsumura
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Patent number: 4612294Abstract: A selenium-base chalcogenide glass for use as optical fibers suitable for transmitting with low loss infrared rays, particularly that of 10.6 .mu.m in wavelength, is provided. The infrared optical fibers with low transmission loss, which is suitable for practical use, are obtained by incorporating 2 to 100 ppm of at least one of Al Ga, and In into a selenium-base chalcogenide glass, thereby to reduce the absorption due to the vibration of Ge--O bond formed by the contamination with oxygen. The infrared optical fibers made of such a glass material show a transmission loss of 3-4 dB/m which is less than 1/2.5 of the loss (10 dB/m) of a reference glass.Type: GrantFiled: November 26, 1984Date of Patent: September 16, 1986Assignees: Hitachi, Ltd., Hitachi Cable, Ltd.Inventors: Toshio Katsuyama, Shin Satoh, Hiroyoshi Matsumura
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Patent number: 4604577Abstract: A measuring instrument of magnetic field utilizing Faraday rotation is disclosed in which a medium exhibiting Faraday rotation includes at least one thin magnetic garnet film magnetized in a propagation direction of light and having a composition expressed by a general formula R.sub.3-x Q.sub.x (Fe.sub.5-y M.sub.y)O.sub.12 (where R indicates at least one element selected from a group consisting of Y, La, Lu, Ca, Sm and Bi, Q indicates at least one element selected from a group consisting of Gd, Eu, Er, Tm, Tb, Yb, Ho and Dy, M is at least one element selected from a group consisting of Ga, Al, Ge, Si, Sc, Mn, In, V and Cr, the value of x lies in a range expressed by a formula 0.1.ltoreq.x.ltoreq.3.0, and the value of y lies in a range expressed by a formula 0.ltoreq.y.ltoreq.5.0). According to this instrument, stable measured values are obtained independently of temperature variation.Type: GrantFiled: February 1, 1983Date of Patent: August 5, 1986Assignee: Hitachi, Ltd.Inventors: Hiroyoshi Matsumura, Toshio Katsuyama, Norio Ohta, Tsuneo Suganuma, Kazuyuki Nagatsuma, Yutaka Sugita
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Patent number: 4581579Abstract: In a magnetic-field measuring apparatus having a Faraday rotation property, a medium having the Faraday rotation property includes at least one magnetic garnet thin film having a composition represented by a general formula of R.sub.3 (Fe.sub.5-x M.sub.x)O.sub.12 (where R is at least one element selected from a group consisting of La, Sm, Lu, Ca and Bi, or at least two elements selected from the group with Y being added thereto, M is at least one element selected from a group consisting of Ga, Ge, Al, Si, Sc, In and Cr, and a range of x is 0.ltoreq.x.ltoreq.1.5), and magnetized in a direction of light transmission, whereby an overall temperature characteristic of a ratio (4.pi.Ms/Ho) of a saturation flux density 4.pi.Ms to a collapse field Ho of a strip domain of the thin film is improved. The magnetic-field measuring apparatus offers a stable measurement of magnetic-field irrespective of a temperature change.Type: GrantFiled: October 26, 1983Date of Patent: April 8, 1986Assignees: Hitachi, Ltd., Hitachi Cable, Ltd.Inventors: Kazuyuki Nagatsuma, Hiroyoshi Matsumura, Tsuneo Suganuma, Norio Ohta, Keikichi Ando, Yuzuru Hosoe, Yutaka Sugita
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Patent number: 4570064Abstract: An electric-field measuring apparatus utilizing electrooptic effect for measuring the intensity of an electric DC field includes a material exhibiting both electrooptic effect and photoelectric effect or both a material exhibiting the electrooptic effect and a material exhibiting the photoelectric effect which material or materials are irradiated with a continuous light ray of a wavelength capable of inducing the electrooptic effect and an intermittently interrupted light ray of a wavelength capable of inducing the photoelectric effect.Type: GrantFiled: July 13, 1983Date of Patent: February 11, 1986Assignees: Hitachi, Ltd., Hitachi Cable, Ltd.Inventors: Kazuyuki Nagatsuma, Hiroyoshi Matsumura, Toshio Katsuyama, Tsuneo Suganuma
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Patent number: 4505729Abstract: A method of producing a preform for a single-polarization optical fiber wherein a glass rod to become a core or a glass rod to become a clad is inserted into a quartz tube which has on its inner wall surface a glass thin film to become a clad layer, a glass thin film to become a jacket layer or glass films to become a jacket layer and a clad layer, and wherein under a state under which the internal pressure of the quartz tube is reduced, the quartz tube is heated to become solid, whereby at least one of the clad and the jacket of the optical fiber preform becomes elliptic in cross section.Type: GrantFiled: October 14, 1983Date of Patent: March 19, 1985Assignee: Hitachi, Ltd.Inventors: Hiroyoshi Matsumura, Toshio Katsuyama, Tsuneo Suganuma
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Patent number: 4483617Abstract: In an optical gyroscope comprising a coil of an optical fiber having opposite ends on which linearly polarized input light beams are incident and from which output light beams are derived which create an interference pattern to be detected, the optical fiber has orthogonal principal axes along which the light beams propagate at a large propagation constant difference. The application of the linearly polarized input light beams to the opposite ends of the optical fiber coil is such that the polarization plane of the linearly polarized light beam coincides with the same principal axis on the opposite ends. Thus, polarization characteristics of the output light beam from the optical fiber coil becomes time invariant and the light paths for the two light beams coincide with each other. In particular, in order to minimize the influence of external disturbances, the optical fiber has a structure defined by.vertline.N.sub.x -N.sub.y .vertline.>.lambda./R.sub.owhere N.sub.x and N.sub.Type: GrantFiled: March 3, 1982Date of Patent: November 20, 1984Assignee: Hitachi, Ltd.Inventors: Hiroyoshi Matsumura, Toshio Katsuyama, Tsuneo Suganuma
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Patent number: 4426129Abstract: A glass layer is formed inside a silica glass tube and another glass layer having a refractive index higher than that of the abovementioned glass layer is formed on said glass layer. After these glass layers are formed, one end of the glass tube is collapsed. While the internal pressure of the glass tube is being reduced below the atmospheric pressure, the glass tube is caused to collapse by heating, thereby yielding a preform for an optical fiber. The optical fiber produced from this preform has the difference in the refractive indices of the two orthogonal major axes of at least 1.6.times.10.sup.-4 and maintains the linear polarization plane.Type: GrantFiled: January 9, 1981Date of Patent: January 17, 1984Assignee: Hitachi, Ltd.Inventors: Hiroyoshi Matsumura, Toshio Katsuyama, Tsuneo Suganuma
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Patent number: 4406518Abstract: A single-mode-transmission optical fiber comprises a core of a radius a having an arbitrary (non constant) refractive index distribution n(r) in the radial direction r, the index distribution being expressed by n.sup.2 (r)=n.sub.1.sup.2 {1-2.DELTA..sub.o f(r)}, and a cladding having a constant refractive index n.sub.2, the radius a of the core being: ##EQU1## In these expressions, n.sub.1 denotes a maximum refractive index of the core, .lambda.Type: GrantFiled: February 20, 1981Date of Patent: September 27, 1983Assignee: Hitachi, Ltd.Inventors: Hiroyoshi Matsumura, Toshio Katsuyama, Tsuneo Suganuma
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Patent number: 3941474Abstract: By heat treating a glass member containing at least one kind of cation to constitute a modifying oxide in contact with a source of another kind of cation to cause ion substitution, a light-conducting glass structure can be produced to have a refractive index distribution wherein the index varies progressively transversely to the intended light path, which is thereby bent toward the direction of increase of the index, such a light-conducting glass structure is not accompanied by differences or lagging of phase velocities of conducted light rays, spreading of the light flux width, and reflection losses.Type: GrantFiled: May 26, 1971Date of Patent: March 2, 1976Assignee: Nippon Selfoc Kabushiki KaishaInventors: Ichiro Kitano, Ken Koizumi, Hiroyoshi Matsumura