Abstract: A semiconductor laser device includes unit semiconductor lasers having facets and having side surfaces, active layers disposed in the respective unit semiconductor lasers so that the ends of the active layers are exposed to the facets of the respective unit semiconductor lasers and having centers at the facets. Two adjacent columns respectively include unit semiconductor lasers in the same number which are laminated so that light is emitted from each of the unit semiconductor lasers in the same direction. The active layer in the facet of each unit semiconductor laser is located at a position closer to the adjacent column than the center of the facet of the unit semiconductor laser. Therefore, as compared with the prior art array type semiconductor laser device in which the central point of the active layer is located at the center of the facet, i.e., at the center between the side surfaces of the unit semiconductor laser, a region where the active layers are distributed, i.e.

Abstract: A semiconductor laser device includes a semiconductor laser chip containing a diode having a polarity; a heat sink on which the semiconductor laser chip is mounted at an interface of the semiconductor laser chip and the heat sink, the heat sink including a pn junction generally parallel to the interface; and a block on which the heat sink is mounted, wherein the diode of the semiconductor laser chip and the pn junction are electrically connected in parallel and in opposite polarity so that the pn junction of the heat sink functions as a reverse current blocking diode for the semiconductor laser chip.

Abstract: The present invention relates to a semiconductor laser control method used preferably for a reading control system such as a bar code reading device and to a semiconductor laser control device employing the above method. The object of the invention is to provide a semiconductor laser control device which can be controlled based on the output of a semiconductor laser, provides a stable laser output in a noise environment, enables easy output adjustment, and is immune to external thermal or electrical noises. In the semiconductor laser control method where the light amount of a light amount to current controllable semiconductor laser is subjected to a feedback control with a predetermined time constant while it is monitored, when the light amount is less than a predetermined value, the semiconductor laser is subjected to an feedback control with a first time constant. When the light amount is more than a predetermined value, the semiconductor laser is subjected to a feedback control with a second time constant.

Abstract: It is the object of the invention to provide a semiconductor laser with a low threshold lasing current and a high external differential quantum efficiency. A n-type AlGaInP clad layer 2, a AlGaInP MQW active layer 3, a p-type AlGaInP clad layer 4, p-type GaInP hetero-buffer layer 5 and a-type GaAs layer 6 are successively grown on a n-type GaAs substrate 1, wherein Al contents of a barrier in the MQW layer 3 is so varied that holes are uniformly distributed in each quantum well. Next, a mesa is formed by an etching process, then a n-type GaAs block layer 7 is grown, and electrodes are formed on both p and n-side surfaces. Finally, the processed substrate is cleaved, and laser diodes are obtained therefrom. An Al content of the barrier layer in the MQW active layer 3 is slowly decreased from a p-side to a n-side, and thereby holes are uniformly distributed in each quantum well and few electrons overflow a quantum well. The selected drawing is FIG. 6.

Abstract: An optical filter, such as a wavelength-division multiplexer, demultiplexer, or optical router, in which several single-mode waveguides are coupled to the sides of an optical interaction region containing a wavelength dispersive element that collects light from one or more input waveguides inputting light to the interaction region and disperses it according to wavelength to one or more output waveguides outputting wavelength-separated light. According to the invention, a multi-moded waveguide is interposed between one or more of the single-moded waveguides and the optical interaction region. It has a predetermined length to create at one end a multiply peaked image of a singly peaked profile presented to it at the other end, thus being a multi-mode interference (MMI) filter that presents a flatter filter profile at the interface between the MMI and the optical interaction region and affords reduced filter sensitivity to wavelength drift of an optical signal.

Abstract: A method is provided for reducing the polarization shift between different modes of an optical signal propagating in an optical grating having a plurality of waveguides extending in a common plane. The method includes the step of imparting curvature to the optical grating along a line that traverses the plurality of waveguides in a direction that is substantially perpendicular to the direction in which the optical signal propagates. The curvature varies in a nonuniform manner along the line to which it is imparted. The curvature may vary in a substantially linear manner along this line, which in some cases may define a symmetry axis of the grating. Sufficient curvature may be imparted to substantially eliminate the polarization shift. The curvature may be imparted by flexing the optical grating at two contact points respectively located near a longest and shortest of the plurality of waveguides.

Abstract: A single-frequency semiconductor laser diode structure and a method for its fabrication. The structure includes a built-in etalon, which limits the frequency of operation of the device to a very narrow frequency band. For an edge-emitting diode, the etalon is formed over a cleaved end face of the semiconductor diode structure, and light is emitted from an opposed cleaved end face. For a surface emitting diode, the etalon is formed as an additional plurality of layers between a plurality of semiconductor layers forming the diode and a substrate on which the structure is formed. Transverse channels formed in the structure have side surfaces that act as mirrors, at least one of which is angularly inclined to the plane of the active region, to reflect light through the etalon layers and out through a parallel exterior surface of the structure. Multiple surface emitting lasers may be arrayed in closely spaced relation to each other, to form a powerful light emitting array.

Abstract: A laser diode array includes a dielectric block with a "direct bonded" conductor layer. The conductor layer is segmented by diode bar spaces cut through it, and a laser diode bar is positioned in each space. Current through the conductor layer energizes the laser diode bars. In one form, the laser diode array and the conductor layer form a conductor ring surrounding a laser medium which is energized by the laser diode bars. In another form, a coolant flow tube within the conductor ring forms an annular coolant channel around the enclosed laser medium. In still another form, the conductor ring is itself surrounded by coolant channels.

Abstract: An apparatus and method for stabilizing the transverse mode of laser oscillation in a vertical cavity semiconductor laser and a microchip laser are disclosed. A preferred embodiment includes a quantum-well region formed over a semiconductor substrate. A first reflective surface is formed over the quantum-well region, and a second reflective surface is formed over the substrate, opposite the first reflective surface, forming a laser cavity. The quantum-well region is optically pumped, producing laser oscillation. The absorbed pump power causes a thermal lensing effect within the semiconductor material, stabilizing the transverse spatial mode of the laser cavity. The radius of curvature of the thermal lens is a function of absorbed pump power. Maximum power conversion efficiency is achieved if the pump power is controlled such that the diameter of the oscillating mode matches the diameter of the pump beam. The invention has applications in optical communication and laser printing.

Abstract: A surface emitting semiconductor laser, with a resonator cavity transverse to the planar extent of the deposited layers, is provided with a first reflection mirror on the substrate side composed of alternating layers comprising a first layer that is made of a Group III-V compound semiconductor and a second layer that is made of a Group III-V compound semiconductor with an energy bandgap that is larger than that of the first layer. A second reflection mirror is provided at the opposite end of the cavity adjacent to a column like resonator portion. At least the first reflection mirror comprises a distributive Bragg reflection (DBR) multiple layer mirror that has an interface region between first and second layers having a carrier concentration that is higher than that of other regions. The column like resonator portion is surrounded by a buried layer which may consist of two layers, the first layer functioning as barrier layer and the second layer functioning as a flattening layer.

Abstract: A method for reducing the inherent polarization shift caused by birefringence between the TE and TM modes of an optical signal propagating in an optical grating which has a plurality of waveguides includes the step of: irradiating the waveguides of the optical grating for different periods of time to induce a compensating polarization shift that substantially reduces the inherent polarization shift. If desired, a compensating polarization shift may be induced which not only reduces but also substantially eliminates the inherent polarization shift.

Abstract: A semiconductor laser comprises: a first cladding layer of a first conduction type; an active layer stacked on the first cladding layer; and a second cladding layer of a second conduction type stacked on the active layer. The first cladding layer, the active layer and the second cladding layer are made of II-VI compound semiconductors. Pulse oscillation occurs with characteristics of a threshold current I.sub.th (A), a threshold voltage V.sub.th (V) of the diode composed of the first cladding layer, the active layer and the second cladding layer, a differential resistance R.sub.S (Q) of the diode after the rising, a thermal resistance R.sub.t (K/W) and a characteristic temperature T.sub.0 (K). When two amounts .alpha. and .beta. are defined by:.alpha..ident.(R.sub.t /T.sub.0)I.sub.th v.sub.th.beta..ident.(R.sub.t /T.sub.0)R.sub.S I.sub.th.sup.2the point (.alpha., .beta.) exists in an area on the .alpha.-.beta. plane surrounded by the straight line .alpha.=0, the straight line .beta.

Abstract: An infrared emitting device and method. The infrared emitting device comprises a III-V compound semiconductor substrate upon which are grown a quantum-well active region having a plurality of quantum-well layers formed of a ternary alloy comprising InAsSb sandwiched between barrier layers formed of a ternary alloy having a smaller lattice constant and a larger energy bandgap than the quantum-well layers. The quantum-well layers are preferably compressively strained to increase the threshold energy for Auger recombination; and a method is provided for determining the preferred thickness for the quantum-well layers. Embodiments of the present invention are described having at least one cladding layer to increase the optical and carrier confinement in the active region, and to provide for waveguiding of the light generated within the active region.

Abstract: A semiconductor laser comprises AlGaAs-type semiconductor layers deposited on a substrate and a current constriction layer having at least one stripe-shaped current injection region. This semiconductor layers comprise: a first cladding layer of the first conductivity type, a first optical waveguide layer of the first conductivity type formed on the first cladding layer, an active layer formed on the first optical waveguide layer and having a quantum-well structure, a second optical waveguide layer of a second conductivity type formed on the active layer, a second cladding layer of the second conductivity type formed on the second optical waveguide layer, and a contact layer formed on the second cladding layer. The active layer has flatness of such a degree that roughness with respect to a reference surface within a unit area of 1 mm.times.1 mm is no more than .+-.0.1 .mu.m, the width of the current injection region of the current constriction layer is between 100 .mu.m to 250 .mu.

Abstract: A semiconductor laser such as a laser diode includes a semiconductor substrate and a laser diode region disposed on said semiconductor substrate and having a laser beam emission end. The semiconductor substrate has a front surface directly below said laser beam emission end, said front surface being retracted from said laser beam emission end. The front surface may be formed as an optically roughened surface as a side wall surface of a groove when the groove is defined in the semiconductor substrate by dicing. The laser diode region includes an active layer of GaAs or AlGaAs. The front surface may further be optically roughened by etching or sputtering.

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 semiconductor laser system for use in an optical pickup is provided which allows the optical pickup to dispense with an expensive optical component such as a beam splitter and to assure accurate tracking sero and focusing servo functions using the SCOOP method, and which includes at least three light-emitting parts formed on one chip and respectively adapted to emit laser beams in a same direction, wherein light-emitting faces of at least two of the light-emitting parts form a step therebetween in the direction in which the laser beams are emitted, and wherein at least two, different in combination from the at least two of the light-emitting parts, of the light-emitting parts are located offset to each other in a direction perpendicular to a plane defined by the direction and the at least two of the light-emitting parts forming the step, while the light-emitting faces of which lie in a plane perpendicular to the direction in which the laser beam are emitted.

Abstract: A remote split scan detector is disclosed which utilizes two rectangular cross section light pipes to transfer the light beam from a raster output scanner (ROS) housing onto two light sensors outside of the housing. Each one of the light pipes is designed to receive a light beam at its input end and transfer the light beam to an output end where the light beam exits the light pipe through a diffused portion of a side wall. Two sensors are placed in such a manner that each faces one diffused surface to receive the light beam exiting the diffused surface.

Abstract: A distributed-feed back semiconductor laser diode comprises a substrate of n-type conductivity GaAs having a pair of opposed surfaces, a pair of sides and a pair of ends. In sequence on one of the opposed surfaces are a first clad layer of n-type conductivity graded AlGaAs; a first confining layer of undoped AlGaAs; a first quantum well layer of undoped GaAs; a barrier layer of undoped AlGaAs; a second quantum well layer of undoped GaAs; a second confining layer of undoped AlGaAs; a spacer layer of p-type conductivity graded AlGaAs; a plurality of spaced, parallel grating bars of p-type conductivity AlGaAs extending across the spacer layer parallel to the ends of the substrate; a second clad layer of p-type conductivity graded AlGaAs over and between the grating bars; and contact layer of p+ type conductivity GaAs. A first conductive contact layer contacts the contact layer and a second conductive contact layer is on the other opposed surface of the substrate.

Abstract: A surface-emitting semiconductor light emitting device comprises an n-type ZnSe buffer layer, n-type ZnSSe layer, n-type ZnMgSSe cladding layer, n-type ZnSSe waveguide layer, active layer, p-type ZnSSe waveguide layer, p-type ZnMgSSe cladding layer, p-type ZnSSe layer, p-type ZnSe contact layer, p-type ZnSe/ZnTe MQW layer and p-type ZnTe contact layer, sequentially stacked on an n-type GaAs substrate. A grid-shaped p-side electrode and a Au film convering the p-side electrode are provided on the p-type ZnTe contact layer. An n-side electrode is provided on the back surface of the n-type GaAs substrate. The active layer has a single quantum well structure or a multiple quantum structure including ZnCdSe quantum well layers.