Abstract: A light-emitting diode array comprising a conductive layer formed on a substrate, a plurality of separate light-emitting parts formed on the conductive layer, a first electrode formed on at least part of a top surface of each light-emitting part, and a second electrode formed on the conductive layer near the light-emitting part, the second electrode being a common electrode for operating a plurality of the light-emitting parts, and regions of the conductive layer between the adjacent light-emitting parts being removed.

Abstract: The present invention relates to an array waveguide grating and a method of manufacture thereof, in which a substantially smooth wavelength-loss characteristics is obtained in a pass band, rather than increasing the loss. In an array waveguide grating (10), wavelength multiplex division signal light is demultiplexed by a channel waveguide array (15), reflected by a Fabry-Perot resonator array (16), and passed through the channel waveguide array (15) again, so that a substantially smooth wavelength-loss characteristic is obtained in the pass band, rather than increasing the loss.

Abstract: A method for growing a compound semiconductor single crystal comprising cooling a starting material melt of a compound semiconductor with an upward increasing temperature gradient in a crystal-growing container having a seed crystal placed at a lower end, thereby growing a single crystal upward from the seed crystal, the crystal orientation of the seed crystal in a crystal growth axis direction being an offset orientation of <100>+&thgr;, wherein the offset angle &thgr; is 2°≦&thgr;≦55°.

Abstract: A method of producing an elliptic core type polarization-maintaining optical fiber comprises the steps of providing a glass rod comprising a cladding glass layer around the periphery of a core glass layer, the cladding glass layer having a softening point higher than the softening point of the core glass layer, removing two side surface portions of the glass rod by machining along the axial direction of the glass rod to form a machined rod noncircular in cross section, outside depositing fine silica glass particles on the periphery of the machined rod, followed by sintering to provide a support glass layer having a softening point higher than the softening point of the cladding glass layer, and drawing the thus obtained glass rod body as an optical fiber preform. Since the portion for constituting the core of the optical fiber is formed by machining, the core is permitted to have a high ellipticity.

Abstract: Each fiber-optic gyroscope unit is shaped like a tetragonal cone. A square plate (51) is used as a base which holds a light source module (52), a light receiving unit (detector) (53) and an optical fiber coil (54). Directional couplers (56a), (56b) are also mounted on the base (51). A phase modulator (55) which includes a piezoelectric element is disposed inside the optical fiber coil (54). A signal processing circuit board (58) which has pedestals (59) stands on the base (51) such that it positions above the optical fiber coil (54). A polarizer (510) is wound around the optical fiber coil (54). A reinforcement member (511) is also provided. All these components are so arranged as not to extend out of the tetragonal cone (OABCO*) which defines its own unit region. Three identical fiber-optic gyroscope units are combined by connecting members (512, 513, 514) to form a single fiber-optic gyroscope to detect rotational angular velocities about three orthogonal axes.

Abstract: A duplexed bus type network in which a main transmission line and a stand-by transmission line are interconnected by a repeater (30), a changeover switch (40) or a two-way amplifier, a modem at each station is duplexed and connected to the main transmission line and the stand-by transmission line, and, upon trouble in one modem (11A), only the relevant station is switched over to the modem (21A) belonging to the stand-by transmission line. When the main transmission line is broken, all the stations are simultaneously switched over to the stand-by transmission line.

Abstract: An optical fiber type magneto-optical head is capable of realizing satisfactory reductions in size and weight of a movable portion of an optical head. An extinction-type form of the optical fiber type magneto-optical head comprises a first optical device for condensing a polarized light beam and leading the light beam into a polarization-maintaining optical fiber, a second optical device for focusing light emerging from the optical fiber into a beam spot on a magnetic recording medium, a detector for detecting via the optical fiber light reflected from the magnetic recording medium with a change in polarized state, and an azimuth rotator disposed between the second optical device and the optical fiber, wherein the azimuth rotator is designed so that the angle of optical rotation upon one pass therethrough is.theta.k/2.+-.n.multidot.45.degree.where.theta.k/2.+-. : the Kerr rotation angle of a magnetic recording film of the recording medium,N= 0, 1, 2, . . . .

Abstract: The fiber-optic rotation sensor comprises a sensing loop using an optical fiber which essentially performs a single polarization when bent, both end portions of the sensing loop being disposed with the principal axes of polarization thereof orthogonal to each other and the end portions being joined by an evanescent wave coupling to form a ring interferometer, a device for introducing to an input end of the interferometer a linearly polarized light at a bearing of 45.degree. relative to the principal axis of polarization of the interferometer, and a retardation measuring system provided at an output end of the interferometer for picking up an electrical output proportional to a rotational angular velocity applied to the interferometer. When the linearly-polarized light is introduced to the input end of the coupling portion of the ring interferometer at a bearing of 45.degree.

Abstract: A core waveguide having a substantially rectangular cross section, with the width thereof greater than the thickness thereof, is provided in a cladding formed on a substrate, and a rare earth element-doped layer is provided in the core waveguide along the waveguiding direction of the waveguide. With the width of the core waveguide set greater than the thickness of the core waveguide, good optical confinement in the width direction of the waveguide is obtained, which enables light to be absorbed by the rare earth element-doped layer efficiently and concentratedly. It is thereby possible to achieve a marked improvement in the excitation efficiency of excitation power. Thus, an enhanced excitation efficiency is achieved with less addition of a rare earth element, and a high-gain optical amplification waveguide free of concentration extinction is provided.

Abstract: A high pin count and multi-layer lead frame according to the present invention which has a short pitch, high density lead pattern and at the same time, enhanced transmission characteristics for high-frequency signals includes at least one pair of conductive layers for grounding, power supply or both of them and one pair of insulating layers formed on these conductive layers, inner leads formed on the insulating layer on the top conductive layer by etching or vapor deposition in a short pitch, high density pattern, and outer leads made of metal frame. The inner leads are electrically connected to the leads for signals of the outer leads, the leads for grounding and power supply of the outer leads are connected to each of the conductive layers separately, and a plurality of holes for wire bonding the electrodes of a semiconductor element to each of the conductive layers are formed on each of the insulating layers.

Abstract: A method of receiving wavelength multiplex signals is designed to receive together, at an end of an optical fiber transmission path, optical information signals transmitted in multiple wavelengths, which correspond to multiple kinds of information, from a plurality of information sources distributed at a virtually constant interval along the transmission path in response to an optical trigger signal. Each of the optical information signals is sampled at a time interval that is in inverse proportion to the light velocity which depends on the wavelength of the signal, so that the content, kind and source of information are identified at the signal reception.

Abstract: A detector for detecting an extraordinary approach of objects having earth potential toward a power transmission line comprises a charging current detection circuit for measuring variations in a charging flowing from the power transmission line into a stray capacitance formed between a detector casing and the earth and a transmitter for sending the value measured by the charging current detection circuit to a receiver installed outside the detector casing by wireless means or a wire. The detector is always able to monitor the extraordinary approach of objects such as trees toward the power transmission line, thereby preventing in advance the accidental grounding of the line.

Abstract: A fiber optic distributed temperature sensor system outputs a temperature distribution along the longitudinal direction of a sensor optical fiber by measuring the temperature dependency of Raman scattered light intensity produced in an optical fiber by use of the OTDR technique. The system is characterized in that a light output from a light source is input to the sensor (optical fiber) via an optical wavelength division demultiplexer, that among the reflected light of back scattered light returning from the sensor optical fiber, light of a particular wavelength range is reflected or transmitted by at least one optical filter of the optical wavelength division demultiplexer to separate the light of the particular wavelength range and that signal of the light of the particular wavelength range is guided to a detector of an optical measuring system.

Abstract: In a focusing error detecting method for an optical head wherein a laser beam from a laser light source is applied to a magneto-optical recording medium to form an image as a light spot thereon, and a focusing error is detecting according to a reflected light from the magneto-optical recording medium, the focusing error detecting method includes a step of dividing the reflected light from the magneto-optical recording medium into a 0-th order light, a +1-st order light and a -1-st order light by a diffraction grating, a step of applying the +1-st order light and the -1-st order light to a first detector and a second detector, respectively, the first and second detectors being arranged before and behind a beam emitting position of the laser light source, respectively and a step of computing outputs from the first and second detectors to obtain a focusing error signal.

Abstract: A method of fabricating an undoped or impurity-doped semi-insulating GaAs single crystal with the use of a silica boat comprises the steps of making a melt of GaAs in the silica boat except for a seed crystal, doping the melt with oxygen, maintaining the doped melt as it is for a predetermined period of time, solidifying the melt from the side opposite the seed crystal toward the seed crystal, seeding the melt when the melt attains a predetermined melt zone width on the seed crystal side, and moving the melt zone in the direction opposite the seed crystal for its solidification while keeping the melt zone width unchanged.

Abstract: An LED array chip comprising; a first semiconductor layer having p-type conduction; a second semiconductor layer having a n-type conduction, possessing forbidden band width smaller than the first layer and provided on the first layer, so as to form a semiconductor chip having a pn junction at the interface with the first layer; the second layer being divided into a first region and a second region by etching the second layer through to the pn junction, the first region thereof being divided to form individual plural LEDs of predetermined configuration, and the n-type layer in the second region being converted to the p-type layer as so to serve as a common region; individual electrodes respectively provided to the surfaces of the LEDs; and a common electrode provided to the common region, parts of the exposed surface of the p-type layer corresponding to the LEDs serving as light emitting surfaces.

Abstract: A multi-port fiberoptic rotary joint comprising a trapezoid prism provided between a rotative member and a fixed member of the rotary joint so as to be rotatable relative to the rotative member and coaxial with said rotative member, a speed change gear mechanism for transmitting the rotation of the rotative member to the trapezoid prism so as to rotate the trapezoid prism at an angular velocity half the angular velocity of the rotative member, rhomboid prisms provided on the entrance side of the trapezoid prism so as to optically guide the light coming from a region outside an aperture of the trapezoid prism to the trapezoid prism as the light parallel to the axis of the trapezoid prism within the aperture thereof, and the rhomboid prisms provided on the exit side of the trapezoid prism so as to optically guide the light emanating from the trapezoid prism to a region outside the aperture of the trapezoid prism, a plurality of pairs of convergent lenses respectively provided to the rotative member and the fixe

Abstract: Two opposite portions of the surface of a core rod whose section is circular are removed by machining in the longitudinal direction thereof, so that the section of the core rod is transformed into a non-circular shape. On the surface of the thusly shaped non-circular core rod, glass particulates are accumulated, and then the glass particulates accumulated on the core rod are sintered to create a preform. Then, the preform is heated and drawn, so that a polarization-maintaining optical fiber of non-circular section is obtained.

Abstract: A rotary joint for polarization plane maintaining optical fibers which can couple two polarization plane maintaining optical fibers to each other while maintaining the polarization plane maintaining property. The rotary joint comprises a rotary member, a fixed member, two optical fiber collimators and a 1/2 wavelength plate for coupling a polarization plane maintaining optical fiber connected to the rotary member with another polarization plane maintaining optical fiber connected to the fixed member, and gears for rotating the 1/2 wavelength plate at a speed equal to one half the rotational speed of the polarization plane maintaining optical fiber on the rotary member side.

Abstract: A polarized wave preserving fiber has a core at its center, cladding, an oval jacket, and a support member in order to improve transmitting property of the polarized single mode by adjusting the refractive index distribution and the ellipticity of the oval jacket.