Abstract: An InGaAlN-based semiconductor laser device, comprising a first layer of a first conductivity type, an active layer having a smaller forbidden band than that of the first layer, and a second layer of a second conductivity type having a larger forbidden band than that of the active layer. The second layer includes a flat region and a stripe-shaped projecting structure. A stripe-shaped optical waveguide forming layer of the second conductivity type having a larger refractive index than that of the second layer is formed on the stripe-shaped projecting structure. A current-constricting layer of the first conductivity type or of a high resistance is formed for covering a top surface of the flat region of the second layer, a side surface of the projecting structure of the second layer, and a side surface of the optical waveguide forming layer.

Abstract: A nitride semiconductor laser device using a group III nitride semiconductor also as a substrate offers excellent operation characteristics and a long laser oscillation life. In a layered structure of a group III nitride semiconductor formed on a GaN substrate, a laser optical waveguide region is formed elsewhere than right above a dislocation-concentrated region extending so as to vertically penetrate the substrate, and electrodes are formed on the top surface of the layered structure and on the bottom surface of the substrate elsewhere than right above or below the dislocation-concentrated region. In a portion of the top surface of the layered structure and in a portion of the bottom surface of the substrate right above and below the dislocation-concentrated region, dielectric layers may be formed to prevent the electrodes from making contact with those regions.

Abstract: The present nitride semiconductor light emitting device includes a nitride semiconductor thick film substrate and a light emitting layered structure including a plurality of nitride semiconductor layers stacked on the substrate. The nitride semiconductor substrate includes at least two layer regions including a first layer region of a high impurity concentration and a second layer region of an impurity concentration lower than the first layer region. The light emitting layered structure is formed on the first layer region of the substrate.

Abstract: A nitride compound semiconductor light emitting device of the present invention includes: a nitride compound semiconductor substrate; and a light emitting device section including a nitride compound semiconductor provided on the nitride compound semiconductor substrate. The nitride compound semiconductor substrate contains a group VII element as an impurity.

Abstract: A semiconductor laser device of the present invention includes, in this order: a GaN layer; an Alx1Ga1-x1N (0.05≦x1≦0.2) lower cladding layer; an Iny1Ga1-y1N (0<y1<1) lower guide layer (thickness: d1 [&mgr;m]); an active layer (thickness: Wa [&mgr;m]) have a multilayer structure comprising of alternating layers of a well layer and a barrier layer, the well layer comprising Als1Inb1Ga1-a1-b1N1-e1-f1Pe1Asf1 (0≦a1, 0≦b1, a1+b1≦1, 0≦e1, 0≦f1, e1+f1<0.5), and the barrier layer comprising Ala2Inb2Ga1-a2-b2N1-e2-f2Pe2Asf2 (0≦a2, 0≦b2, a2+b2≦1, 0≦e2, 0≦f2, e2+f2<0.5); an Iny2Ga1-y2N (0<y2<1) upper guide layer (thickness: d2 [&mgr;m]); and an Alx2Ga1-x2N (0.5≦x2≦0.2) upper cladding layer, wherein: the thicknesses and the compositions of the lower guide layer and the upper guide layer are set such that ripples in a far field pattern in a direction perpendicular to a stack plane are suppressed.

Abstract: A semiconductor light emitting element, includes: a substrate; a first conductive semiconductor layer formed on the substrate; a strained emission layer formed on the first conductive semiconductor layer; and a second conductive semiconductor layer formed on the strained emission layer, wherein the strained emission layer includes: an element other than a constituent element of the substrate; and a rare earth element.

Abstract: A GaN light-emitting device is provided having a low specific contact resistance of an n-type electrode as well as a low threshold voltage or threshold current density. The GaN light-emitting device has an electrode formed on a nitrogen-terminated surface of a GaN substrate. Specifically, the GaN light-emitting device includes the GaN substrate, a plurality of GaN compound semiconductor layers formed on the GaN substrate, and the n-type electrode and a p-type electrode, wherein the semiconductor substrate is of n-type and the n-type electrode is formed on the nitrogen-terminated surface of the semiconductor substrate. The concentration of n-type impurities in the substrate preferably ranges from 1×1017 cm−3 to 1×1021 cm−3.

Abstract: A nitride semiconductor light emitting device includes a worked substrate including grooves and lands formed on a main surface of a nitride semiconductor substrate, a nitride semiconductor underlayer covering the grooves and the lands of the worked substrate and a nitride semiconductor multilayer emission structure including an emission layer including a quantum well layer or both a quantum well layer and a barrier layer in contact with the quantum well layer between an n-type layer and a p-type layer over the nitride semiconductor underlayer, while the width of the grooves is within the range of 11 to 30 &mgr;m and the width of the lands is within the range of 1 to 20 &mgr;m.

Abstract: The organic EL emission device includes an organic light emission layer for EL emission sandwiched between first and second electrode layers, at least one of which is transparent. At least the first electrode layer includes a plurality of electrodes arranged with spatial periodicity. The plurality of electrodes included in the first electrode layer together with adjacent regions in the second electrode layer including one or more electrodes form a plurality of electrode pair regions arranged with spatial periodicity. The method of driving the organic EL emission device is characterized in that electric fields having either different strengths or directions are applied with variation in a time-dependent manner to electrode pair regions adjacent to each other among the plurality of electrode pair regions.

Abstract: A nitride semiconductor light emitting device includes a worked substrate including grooves and lands formed on a main surface of a nitride semiconductor substrate, a nitride semiconductor underlayer covering the grooves and the lands of the worked substrate and a nitride semiconductor multilayer emission structure including an emission layer including a quantum well layer or both a quantum well layer and a barrier layer in contact with the quantum well layer between an n-type layer and a p-type layer over the nitride semiconductor underlayer, while the width of the grooves is within the range of 11 to 30 &mgr;m and the width of the lands is within the range of 1 to 20 &mgr;m.

Abstract: An optical information reproduction apparatus includes a semiconductor laser device as a light source which provides oscillation as periodic pulse waves upon application of a DC current. The semiconductor laser device is disposed so that an optical distance L from a light-emitting point of the semiconductor laser device to a recording surface of an optical recording medium satisfies the following relationship: TP<(4L/C) and T>TP+(2L/C), where T is a period of pulse waves which are output from the semiconductor laser device in absence of a returning light from the optical recording medium; TP is a pulse width of the respective pulse waves which is defined as a width of a portion of the respective pulse waves, the portion having intensities which correspond to 10% or more of the peak intensity of the respective pulse waves; and C is a speed of light through air.

Abstract: A ridge waveguide type distributed feedback semiconductor laser device includes a diffraction grating formed on a surface of a semiconductor wafer, a semiconductor layer formed on the diffraction grating, the semiconductor layer serving to alleviate the irregularity of the diffraction grating, and a stripe-like ridge having a cladding layer and a contact layer formed on the semiconductor layer. Also, a method for manufacturing the ridge waveguide type distributed feedback semiconductor laser device is disclosed.

Abstract: The integrated optical control element of this invention includes: a first waveguide for allowing light incident from outside to propagate therein; a multilayer structure for allowing the light which has propagated in the first waveguide to be incident thereon and for transmitting the light therethrough or reflecting the light therefrom, the multilayer structure including at least one layer having a refractive index different from an equivalent refractive index of a region with which the at least one layer is in contact; and a second waveguide for receiving at least part of the light transmitted through or reflected from the multilayer structure.

Abstract: The integrated optical control element of this invention includes: a first waveguide for allowing light incident from outside to propagate therein; a multilayer structure for allowing the light which has propagated in the first waveguide to be incident thereon and for transmitting the light therethrough or reflecting the light therefrom, the multilayer structure including at least one layer having a refractive index different from an equivalent refractive index of a region with which the at least one layer is in contact; and a second waveguide for receiving at least part of the light transmitted through or reflected from the multilayer structure.

Abstract: A gain coupled distributed feedback semiconductor laser includes an active layer and a diffraction grating provided in the vicinity of the active layer and having a plurality of light absorption layers periodically arranged along a resonator length direction. The order of the diffraction grating is one, a duty of the diffraction grating is in the range of about 0.4 to about 0.8, and a thickness of the light absorption layer is in the range of about 6 nm to about 30 nm.

Abstract: An optical data reading method and apparatus for photoelectrically converting reflection light of a laser beam radiated onto a recording medium and thereby reproducing digital data recorded in the recording medium, performing a coherent detection by photoelectrically converting a first laser beam having a light frequency .nu..sub.1 and a second laser beam having a light frequency .nu..sub.2, where .nu..sub.1 -.nu..sub.2 .gtoreq.R (R: rate of reading the digital data), in a state where wavefronts of the first and second laser beams are aligned with each other, detecting temporal changes of either an amplitude or a phase of a beat signal component of the first and second laser beams, having a frequency of (.nu..sub.1 -.nu..sub.2) and being included in an photoelectrically converted output, and reading the digital data recorded in the recording medium based on a result of detection.

Abstract: A quantum wire structure includes a first layer having a thickness sufficiently smaller than a de Broglie wavelength of an electron wave in a medium, a second layer and a third layer which are disposed on and under the first layer and respectively have a forbidden band width larger than that of the first layer, wherein the first layer has a region with a relatively small curvature and a region with a relatively large curvature in its cross-section, and a width of the region with a relatively small curvature is 50 nm or less.

Abstract: A spatial coherent light transmission apparatus according to the present invention, includes: a light transmitter for emitting a data signal as first coherent light; a light receiver for emitting second coherent light having a wavelength little different from that of The first coherent light, mixing and receiving the first and second coherent lights, and performing a coherent detection of the data signal. At least one of the light transmitter and the light receiver has a detection device for detecting at least one of a coherent light transmission state and a coherent light detection state. The apparatus further includes a control device for controlling at least one of the light transmitter and the light receiver based on information of the state detected by the detection device.

Abstract: A spatial optical transmission apparatus includes: a light signal transmitting device for generating a signal beam which is modulated in accordance with a signal to be transmitted and is intensity-modulated with a lower frequency compared with a signal transmission speed; and a light signal demodulating device for receiving the signal beam from the light signal transmitting device by a detector, adjusting the direction of a locally oscillated beam based on the received signal beam so as to have a predetermined relationship with the direction of the signal beam so that intensity-modulated components in an output signal from the detector falls within a predetermined range of intensity, thereby aligning the wavefront of the signal beam with the wavefront of the locally oscillated beam, and extracting signal components which correspond to the transmitted signal from signal components modulated in accordance with the transmitted signal in the signal beam.

Abstract: In an assembly structure of an optical integrated circuit device for assembling a semiconductor laser device and an optical integrated circuit substrate, the semiconductor laser device includes a recessed/raised structure. On the other hand, the optical integrated circuit substrate includes another recessed/raised structure to fit the recessed/raised structure of the semiconductor laser device. These recessed/raised structures are formed so that their cross sections taken parallel to the layers forming the semiconductor laser device are symmetric in shape about the respective optical axes of the semiconductor laser device and the optical integrated circuit substrate. Further, the recessed/raised structures preferably contain a tapered portion as part of its contour, the taper forming a prescribed angle with the respective optical axes. Thus, the mounting accuracy required to achieve the prescribed coupling efficiency in the optical integrated circuit device can be obtained by simple mechanical operations.