Abstract: A lithium-containing complex metal oxide having a crystal structure of &agr;-NaFeO2 type and represented by a general formula: LiaNiXCoYAlZO2 wherein 0.96≦a≦1.06, 0.70≦X<0.85, 0.05≦Y≦0.20, 0.10<Z≦0.25, and 0.98≦(X+Y+Z)≦1.02, and further wherein a separation between a peak position of (018) face and a peak position of (110) face in the powder X-ray diffraction pattern of said metal oxide using CuK&agr;-ray is in the range of from 0.520 to 0.700° as expressed in terms of &Dgr;2&thgr;((110)-(018)).

Abstract: In a distributed feedback semiconductor laser includes an InP substrate and a multiple layer structure formed on a main surface of the InP substrate, the multiple layer structure includes at least an active layer for emitting laser light and a periodical structure for distributed feedback of the laser light, and the periodical structure includes a plurality of semiconductor regions each having a triangular cross section in a direction perpendicular to the main surface of the InP substrate and parallel to a cavity length of the distributed feedback semiconductor laser, the triangular cross section projecting toward the InP substrate.

Abstract: The semiconductor laser of the invention includes: a semiconductor substrate of a first conductivity type; a stripe-shaped multilayer structure, formed on the semiconductor substrate, the stripe-shaped multilayer structure including an active layer; and a current blocking portion formed on the semiconductor substrate on both sides of the stripe-shaped multilayer structure, wherein the current blocking portion has a first current blocking layer of a second conductivity type, and a second current blocking layer of the first conductivity type formed on the first current blocking layer, the first current blocking layer includes a low-concentration region having a relatively low concentration of an impurity of the second conductivity type, and a high-concentration region having an impurity concentration which is higher than that of the low-concentration region, and the low-concentration region is provided at a position closer to the stripe-shaped multilayer structure than the high-concentration region.

Abstract: In a distributed feedback semiconductor laser includes an InP substrate and a multiple layer structure formed on a main surface of the InP substrate, the multiple layer structure includes at least an active layer for emitting laser light and a periodical structure for distributed feedback of the laser light, and the periodical structure includes a plurality of semiconductor regions each having a triangular cross section in a direction perpendicular to the main surface of the InP substrate and parallel to a cavity length of the distributed feedback semiconductor laser, the triangular cross section projecting toward the InP substrate.

Abstract: In a semiconductor laser device 100, an n-type InGaAsP light confinement layer 2, a multiple quantum well active layer 3, a p-type InGaAsP light confinement layer 4, and a p-type InP cladding layer 5 are formed on an n-type InP substrate 1 to be in a mesa structure extending in stripes along the cavity length direction. Moreover, regions on both sides of this striped mesa are buried with a p-type InP current blocking layer 6 and an n-type InP current blocking layer 7. Furthermore, a p-type InP burying layer 8 and a p-type InGaAsP contact layer 9 are formed thereon. The oscillation wavelength of the semiconductor laser device 100 is around 1.3 .mu.m. The stripe width of the active layer 3 is such that the width W1 at the front end face and the width W2 at the rear end face have a relationship of W1<W2, and the stripe width is continuously reduced from W2 to W1 along the cavity length direction.

Abstract: A distributed feedback semiconductor laser which includes a semiconductor substrate of a first conductive type; a semiconductor multi-layer structure provided on the semiconductor substrate and including an active layer for generating laser light; and a gain-coupled diffraction grating provided between the semiconductor substrate and the semiconductor multi-layer structure. The diffraction grating includes a plurality of curved projections periodically arranged at a surface of the semiconductor substrate and a quantum well light absorption layer for covering the plurality of curved projections. The quantum well light absorption layer includes a light absorption area having a first thickness at each border between two adjacent curved projections and a non-light absorption area having a second thickness which is smaller than the first thickness at a top of each of the curved projections.

Abstract: The semiconductor laser of the invention includes: a semiconductor substrate of a first conductivity type; a stripe-shaped multilayer structure, formed on the semiconductor substrate, the stripe-shaped multilayer structure including an active layer; and a current blocking portion formed on the semiconductor substrate on both sides of the stripe-shaped multilayer structure, wherein the current blocking portion has a first current blocking layer of a second conductivity type, and a second current blocking layer of the first conductivity type formed on the first current blocking layer, the first current blocking layer includes a low-concentration region having a relatively low concentration of an impurity of the second conductivity type, and a high-concentration region having an impurity concentration which is higher than that of the low-concentration region, and the low-concentration region is provided at a position closer to the stripe-shaped multilayer structure than the high-concentration region.

Abstract: An electro-absorption optical modulator, where a waveguide length of the absorption layer is denoted by L, a light confinement coefficient thereof is denoted by .GAMMA., and a performance factor of the absorption layer at an applied voltage V to an absorption layer is denoted by K(V), has design parameters selected so that a relationship .vertline.K(V)-.GAMMA..multidot.L.vertline. .ltoreq.0.005 cm is satisfied in a continuous operation range of a quenching ration T.sub.Att. The waveguide length L is preferably optimizrd so as to satisfy K(V).apprxeq..GAMMA..multidot.L in the operation range.

Abstract: A distributed feedback semiconductor laser which includes a semiconductor substrate of a first conductive type; a semiconductor multi-layer structure provided on the semiconductor substrate and including an active layer for generating laser light; and a gain-coupled diffraction grating provided between the semiconductor substrate and the semiconductor multi-layer structure. The diffraction grating includes a plurality of curved projections periodically arranged at a surface of the semiconductor substrate and a quantum well light absorption layer for covering the plurality of curved projections. The quantum well light absorption layer includes a light absorption area having a first thickness at each border between two adjacent curved projections and a non-light absorption area having a second thickness which is smaller than the first thickness at a top of each of the curved projections.

Abstract: The semiconductor laser device of the invention includes: a strained quantum well structure including a well layer and a barrier layer, and a semiconductor substrate for supporting the strained quantum well structure. In the semiconductor laser device, at least one of the well layer and the barrier layer is composed of a mixed crystal where an atomic ordering is generated.

Abstract: A multi quantum well semiconductor laser includes an InP substrate and a multi-layered structure formed on the InP substrate, lasing at 1.29 .mu.m to 1.33 .mu.m wavelength, wherein the multi-layered structure includes at least a multi quantum well active layer, the multi quantum well active layer including InGaAsP well layers and InGaAsP barrier layers alternately provided, the InGaAsP barrier layers are lattice matched with the InP substrate, and a bandgap wavelength of the InGaAsP barrier layers is substantially equal to 1.05 .mu.m.

Abstract: A fine silica tube composed of silica gel and having an outer diameter of 0.05 to 2 .mu.m wherein the cylindrical wall portion of the tube has a cross-section defined by a substantially square outer periphery and a substantially square vacant center, or by a circular outer periphery and a substantially square vacant center; and a fine silica tube composed of silica glass and having an outer diameter of 0.05 to 1.4 .mu.m wherein the cylindrical wall portion of the tube has a cross-section defined by a substantially square outer periphery and a substantially square vacant center. The fine silica gel tube is made by treating a tetraalkoxysilane with ammonia or aqueous ammonia in a water-soluble alcohol medium in the presence of tartaric acid, citric acid, a tartaric acid salt or a citric acid salt, whereby the tetraalkoxysilane is hydrolyzed. The fine silica glass tube is made by calcining the fine silica gel tube at 800.degree. to 1,400.degree. C.

Abstract: The semiconductor laser of the invention includes: a semiconductor substrate of a first conductivity type; a stripe-shaped multilayer structure, formed on the semiconductor substrate, the stripe-shaped multilayer structure including an active layer; and a current blocking portion formed on the semiconductor substrate on both sides of the stripe-shaped multilayer structure, wherein the current blocking portion has a first current blocking layer of a second conductivity type, and a second current blocking layer of the first conductivity type formed on the first current blocking layer, the first current blocking layer includes a low-concentration region having a relatively low concentration of an impurity of the second conductivity type, and a high-concentration region having an impurity concentration which is higher than that of the low-concentration region, and the low-concentration region is provided at a position closer to the stripe-shaped multilayer structure than the high-concentration region.

Abstract: A distributed feedback semiconductor laser which includes a semiconductor substrate of a first conductive type; a semiconductor multi-layer structure provided on the semiconductor substrate and including an active layer for generating laser light; and a gain-coupled diffraction grating provided between the semiconductor substrate and the semiconductor multi-layer structure. The diffraction grating includes a plurality of curved projections periodically arranged at a surface of the semiconductor substrate and a quantum well light absorption layer for covering the plurality of curved projections. The quantum well light absorption layer includes a light absorption area having a first thickness at each border between two adjacent curved projections and a non-light absorption area having a second thickness which is smaller than the first thickness at a top of each of the curved projections.

Abstract: Herein disclosed is a vapor growth system, in which the number of dummy lines is reduced to decrease the number of lines led into a valve system, thereby enabling thin film growth having a good interfacial steepleness. The system comprising gas supplying lines A70, B71 and C72, which are made up of AsH.sub.3 process gas lines A62, B65, C68 and balance lines A61, B64 and C67, respectively. The balance lines A61, B64 and C67 contributes equalization of products of the viscosity and the flow rate in the gas supplying lines A70, B71 and C72, and the dummy line 60. Only when AsH.sub.3 (A), AsH.sub.3 (B) and AsH.sub.3 gases are not fed upon formation of the film growth, the dummy line 60 is connected to the main line. Whereby, the system is free from pressure fluctuation of the gas in the main line, with an arrangement of even a single dummy line.

Abstract: A light-receiving module includes: a pigtail optical fiber including a core portion for transmitting an optical signal and a cladding portion covering a side face of the core portion; an optical connector provided at a first end of the pigtail optical fiber for optically connecting a transmitting optical fiber with the end of the pigtail optical fiber; a light-receiving device having a light-receiving face for receiving the optical signal propagating through the core portion and for converting the optical signal into an electric signal; an optical coupling system for converging the optical signal emitted from a second end of the pigtail optical fiber onto the light-receiving face of the light-receiving device; and means for preventing light propagating through the cladding portion from reaching the light-receiving face of the light-receiving device so that the optical signal propagating through the core portion does not interfere with the light propagating through the cladding portion on the light-receiving f

Abstract: A light-emitting or light-receiving assembly is disclosed wherein the optical axis of input or output light to or from an optical fiber may not be shifted or dislocated under various environmental conditions. An optical isolator 3 is fixed on a lens mount 7 carrying a lens 2 and a ferrule 5 holding the optical fiber 12 therein is fixed to a ferrule holder 6 and the lens mount 7. Then, the distance between the lens 2 and an end surface 4 of the optical fiber is predetermined with a mechanical machining accuracy. This is followed by center-to-center adjustment through the use of a unit holder 8 placed around the lens mount 7. Thereafter, the lens mount 7 is fixedly secured to the unit holder 8 which in turn is fixedly secured to the laser mount 9, through the use of the YAG welding technique. An assembly unit 100 containing a semiconductor laser 1, the lens 2, the optical isolator 3 and the ferrule 4 is mounted on a temperature controlling Peltier effect element 10 by solder welding.

Abstract: The present invention provides a GTP binding protein containing the following amino acid sequence, with a molecular weight of about 22K dalton and having GTP binding activity which is inhibited by N-ethyl-maleimide and GTP hydrolyzing activity:Thr-Ile-Glu-Asp-Ser-Tyr, and a method for the production of a GTP binding protein, which comprises introducing a DNA fragment containing DNA that encodes the GTP binding protein into a cloning site present at the downstream to a promoter of an expression vector, then introducing the expression vector thus constructed into a host, culturing said host, thereby expressing and accumulating the GTP binding protein and then collecting thereof.

Abstract: A method of making a semiconductor device including a plurality of gate electrodes (6a, 6b, 6c, 6d) arranged on the surface of a semiconductor substrate (1) with insulating layers (5, 8) covering the top and the side walls of the gate electrodes. The spaces between the opposing side walls of adjacent gate electrodes on the surface of the element isolation region (2) are smaller than twice the thickness of the thinnest insulating layer (8) among the insulating layers of the side walls of the gate electrodes on the surface of the active regions. The space (14) between the gate electrodes on the element isolation region is filled with the insulating isolation layer (8) so that unevenness in the underlying portion on the element isolation region on which the conductive interconnection layer (10) to be formed is reduced, preventing thinning of the conductive interconnection layer and disconnection due to excessive etching of a resist film in patterning the conductive interconnection layer.

Abstract: A strained multiple quantum well semiconductor laser including a semiconductor substrate, a multiple quantum well active layer including a plurality quantum well layers and a plurality of barrier layers, and a multilayer structure including the above multiple quantum well active layer is provided. Each barrier layer is interposed between two of the multiple quantum well active layers. The multilayer structure is formed upon the semiconductor substrate. Herein, at least one of the plurality of barrier layers is thicker than the other barrier layers, thereby serving as a layer absorbing strain which is stored in the barrier layers due to a difference between the lattice constant of semiconductor substrate and the lattice constant each quantum well layer.