Abstract: A wavelength conversion system includes a Mach-Zehnder interferometer including two optical waveguides, a non-linear medium provided on one of the two optical waveguides, and a branching ratio adjuster for adjusting the branching ratio of multiplexed light produced by multiplexing signal light and pumping light so that the powers of the signal light and the pumping light which are to be emitted from the two optical waveguides are equal to each other. The multiplexed light whose branching ratio is adjusted by the branching ratio adjuster is introduced into the two optical waveguides such that the non-linear medium generates phase conjugation light of the signal light and the light guided through the one optical waveguide and the light guided through the other one of the two optical waveguides interfere with each other so that the phase conjugation light is extracted as wavelength conversion light.

Abstract: A wavelength conversion system includes a Mach-Zehnder interferometer including two optical waveguides, a non-linear medium provided on one of the two optical waveguides, and a branching ratio adjuster for adjusting the branching ratio of multiplexed light produced by multiplexing signal light and pumping light so that the powers of the signal light and the pumping light which are to be emitted from the two optical waveguides are equal to each other. The multiplexed light whose branching ratio is adjusted by the branching ratio adjuster is introduced into the two optical waveguides such that the non-linear medium generates phase conjugation light of the signal light and the light guided through the one optical waveguide and the light guided through the other one of the two optical waveguides interfere with each other so that the phase conjugation light is extracted as wavelength conversion light.

Abstract: An optical waveform reshaping device, including a semiconductor optical waveguide which has an active layer, wherein: optical amplification regions and optical absorption regions are installed alternately along the semiconductor optical waveguide; one optical amplification region is set longer than the other optical amplification regions so that a desired amplification factor can be obtained when power of an input optical signal is at an ON level; a power level is maintained by the other optical amplification regions excluding the one optical amplification region and by the optical absorption regions when the power of the input optical signal is at the ON level; and when the power of the input optical signal is at an OFF level, the input optical signal is absorbed by the optical absorption regions so that a power level of an output optical signal will not be higher than the power level of the input optical signal.

Abstract: A wavelength conversion system includes a Mach-Zehnder interferometer including two optical waveguides, a non-linear medium provided on one of the two optical waveguides, and a branching ratio adjuster for adjusting the branching ratio of multiplexed light produced by multiplexing signal light and pumping light so that the powers of the signal light and the pumping light which are to be emitted from the two optical waveguides are equal to each other. The multiplexed light whose branching ratio is adjusted by the branching ratio adjuster is introduced into the two optical waveguides such that the non-linear medium generates phase conjugation light of the signal light and the light guided through the one optical waveguide and the light guided through the other one of the two optical waveguides interfere with each other so that the phase conjugation light is extracted as wavelength conversion light.

Abstract: An intrinsic GaAs waveguide layer is formed on a p-type AlGaAs cladding layer, a quantum dot active layer is formed further thereon. An n-type AlGaAs cladding layer is formed on the center portion of the quantum dot active layer. Thus-configured semiconductor laser is allowed to successfully suppress the area of the p-n junction plane to a small level, and to obtain a high level of reliability, because there is no need of processing the center portion of the quantum dot active layer, contributive to laser oscillation.

Abstract: A surface-emitting laser has a lower multilayer film reflecting mirror, an active layer, a current confinement layer, a clad layer, an upper multilayer film reflecting mirror, and an upper electrode formed in the order described on the upper surface of a substrate having a lower electrode formed on the lower surface thereof. The current confinement layer includes a conductive part and an insulating part surrounding the conductive part with the conductive part being defined by a sidewall surface that widens along a direction toward the active layer.

Abstract: The optical semiconductor device comprises a lower clad layer 12, optical waveguide layers 14, 16, 18 including an active layer for recombining the carriers. The upper clad layer 20 is mesa stripe configuration having a first mesa portion contacting the contact layer 22 and having a first width, and a second mesa portion having a second width larger than the first width. The first width, the second width and the thickness of the second mesa portion are set not to oscillate in the higher-order transverse mode.

Abstract: The optical semiconductor device comprises an active layer including a plurality of quantum dot stacks 18, 22, 26 each of which is formed of a plurality of quantum dot layers 14 and a plurality of first layers 16 alternately stacked, and a plurality of second barrier layers 20, 24 thicker than the first barrier layers 16 stacked alternately with the quantum dot stacks 18, 22, 26. Thus, the quantum dot layers can be stacked with the generation of dislocations due to lattice mismatching between the substrate and the quantum dots suppressed. A number of quantum dot layers can be stacked with a desired light confinement coefficient ensured. The optical semiconductor device can have the characteristics easily improved.

Abstract: A lower multi-layer mirror is disposed on a substrate made of a first semiconductor having a first lattice constant. The lower multi-layer mirror has a lamination structure that a first layer made of an oxide of a second semiconductor and a second layer made of a third semiconductor are alternately stacked. A strain-relaxation layer is disposed on the lower multi-layer mirror, the strain-relaxation layer being made of a fourth semiconductor having a second lattice constant different from the first lattice constant. An active layer is disposed on the strain-relaxation layer. The active layer including a luminescence region is made of a fifth semiconductor having a third lattice constant different from the first and second lattice constants. An upper multi-layer mirror is disposed on the active layer. A surface-emitting semiconductor laser is provided which has a high efficiency and a low heat resistance.

Abstract: In a pre-replacement process, a replacement battery module is provided with a memory effect before being dispatched, by performing at least one of the process of performing a cyclic charge/discharge operation on the replacement battery module while limiting the width of SOC change to an intermediate range, and the process of setting an initial SOC and then letting the replacement battery module stand for a predetermined time in an environment of temperature above normal temperature. This pre-replacement process substantially eliminates the difference between the voltage characteristic of the replacement battery module yet to be used and the voltage characteristic of a battery module having a history of use, thereby achieving a uniform voltage characteristic of a battery pack as a whole.

Abstract: A surface-emitting laser has a lower multilayer film reflecting mirror, an active layer, a current confinement layer, a clad layer, an upper multilayer film reflecting mirror, and an upper electrode formed in the order described on the upper surface of a substrate having a lower electrode formed on the lower surface thereof. The current confinement layer includes a conductive part and an insulating part surrounding the conductive part with the conductive part being defined by a sidewall surface that widens along a direction toward the active layer.

Abstract: A lower multi-layer mirror is disposed on a substrate made of a first semiconductor having a first lattice constant. The lower multi-layer mirror has a lamination structure that a first layer made of an oxide of a second semiconductor and a second layer made of a third semiconductor are alternately stacked. A strain-relaxation layer is disposed on the lower multi-layer mirror, the strain-relaxation layer being made of a fourth semiconductor having a second lattice constant different from the first lattice constant. An active layer is disposed on the strain-relaxation layer. The active layer including a luminescence region is made of a fifth semiconductor having a third lattice constant different from the first and second lattice constants. An upper multi-layer mirror is disposed on the active layer. A surface-emitting semiconductor laser is provided which has a high efficiency and a low heat resistance.

Abstract: A planar laser diode includes a substrate, a first multilayer structure on the substrate and formed of an alternate stacking of a first epitaxial layer and a second epitaxial layer, a cavity structure provided on the first multilayer structure and including an undoped active layer for producing optical radiation as a result of stimulated emission, a second multilayer structure provided on the cavity structure and formed of an alternate stacking of a third epitaxial layer and a fourth epitaxial layer, a first electrode structure on a bottom surface of the substrate, a second electrode structure for injecting carriers to said active layer via said cavity structure, an optical passage provided in one of the first and second electrode structures for allowing an optical beam to pass therethrough; a a current path structure provided between the second electrode structure and the active layer for providing a passage of the carriers, a current confinement structure for confining the passage of the carriers such that

Abstract: A current constriction layer surrounding a vertical-cavity region is formed in a cladding layer of a surface emitting laser. The forbidden band width of the material forming this current constriction layer is wider than the forbidden band width of a material forming the cladding layer. Further, the current constriction layer and the cladding layer are formed of semiconductors, and conduction types thereof are different from each other. Further, the upper surface of the cladding layer covering the current constriction layer has a step in the periphery of vertical-cavity region.

Abstract: An electrostatic recording sheet is produced by coating the opposite surfaces of a paper sheet with an electroconductive coating composition including a cationic polymer electroconductive agent and a cationic sizing agent to form electroconductive layers and further coating one of said electroconductive layers with a dielectric coating composition in the form of an aqueous polymer dispersion to form a recording layer via a penetration resist layer. The penetration resist layer is formed of a gelated material produced by an ionic reaction on contact of said aqueous polymer dispersion with said electroconductive layer.