Abstract: A driver circuit substrate is prepared and a mirror substrate is so provided as to be placed on the driver circuit substrate. Nine mirror elements are lad out on the mirror substrate in a 3×3 matrix form. The mirror elements are prepared by a microelectromechanical system (MEMS). An insulating substrate is provided on the driver circuit substrate and a driver circuit which drives a light reflecting mirror element is provided on the insulating substrate. The driver circuit substrate is connected to the mirror substrate via a resin layer of a thermosetting adhesive or the like.

Abstract: A gallium nitride type semiconductor laser device includes: a substrate; and a layered structure formed on the substrate. The layered structure at least includes an active layer of a nitride type semiconductor material which is interposed between a pair of nitride type semiconductor layers each functioning as a cladding layer or a guide layer. A current is injected into a stripe region in the layered structure having a width smaller than a width of the active layer. The width of the stripe region is in a range between about 0.2 ?m and about 1.8 ?m.

Abstract: A semiconductor optical amplifier device includes an active layer, an n-type InP substrate, an n-type InP clad layer, a p-type InP clad layer, p-electrodes and n-electrodes. The active layer is made of, e.g., InGaAsP, and includes a saturable absorption region and optical amplification regions. A common modulated current is injected into each optical amplification region through the p-electrode. A modulated current is injected into the saturable absorption region through the p-electrode independently of the optical amplification region. The active layer receives injection light produced by adding additional noise light to an externally applied light signal, and emits output light produced by amplifying the injection light.

Abstract: A gallium nitride semiconductor laser device has an active layer (6) made of a nitride semiconductor containing at least indium and gallium between an n-type cladding layer (5) and a p-type cladding layer (9). The active layer (6) is composed of two quantum well layers (14) and a barrier layer (15) interposed between the quantum well layers, and constitutes an oscillating section of the semiconductor laser device. The quantum well layers (14) and the barrier layer (15) have thicknesses of, preferably, 10 nm or less. In this semiconductor laser device, electrons and holes can be uniformly distributed in the two quantum well layers (14). In addition, electrons and holes are effectively injected into the quantum well layers from which electrons and holes have already been disappeared by recombination. Consequently, the semiconductor laser device has an excellent laser oscillation characteristic.

Abstract: A gallium nitride semiconductor laser device has an active layer (6) made of a nitride semiconductor containing at least indium and gallium between an n-type cladding layer (5) and a p-type cladding layer (9). The active layer (6) is composed of two quantum well layers (14) and a barrier layer (15) interposed between the quantum well layers, and constitutes an oscillating section of the semiconductor laser device. The quantum well layers (14) and the barrier layer (15) have thicknesses of, preferably, 10 nm or less. In this semiconductor laser device, electrons and holes can be uniformly distributed in the two quantum well layers (14). In addition, electrons and holes are effectively injected into the quantum well layers from which electrons and holes have already been disappeared by recombination. Consequently, the semiconductor laser device has an excellent laser oscillation characteristic.

Abstract: A nitride-type compound semiconductor laser device includes a substrate and a layered structure provided on the substrate. A light absorption layer having a bandgap smaller than a bandgap of an active layer in the layered structure is provided in a position between the cladding layer, which is provided on a side opposite to a mount surface with respect to the active layer, and a surface of the layered structure which is opposite to the mount surface.

Abstract: A photonic crystal and a producing method thereof are provided. The photonic crystal includes at least two media of different refractive indices formed on a semiconductor substrate. One of the media is periodically arranged in another one of the media. The photonic crystal has a cleaved surface on its side. The directions of primitive translation vectors representing the periodic arrangement directions of the one medium are at desired angles with the cleaved surface. Preferably, the direction of at least one of the primitive translation vectors is in parallel with the cleaved surface.

Abstract: A gallium nitride type semiconductor laser device includes: a substrate; and a layered structure formed on the substrate. The layered structure at least includes an active layer of a nitride type semiconductor material which is interposed between a pair of nitride type semiconductor layers each functioning as a cladding layer or a guide layer. A current is injected into a stripe region in the layered structure having a width smaller than a width of the active layer. The width of the stripe region is in a range between about 0.2 &mgr;m and about 1.8 &mgr;m.

Abstract: A driver circuit substrate is prepared and a mirror substrate is so provided as to be placed on the driver circuit substrate. Nine mirror elements are lad out on the mirror substrate in a 3×3 matrix form. The mirror elements are prepared by a microelectromechanical system (MEMS). An insulating substrate is provided on the driver circuit substrate and a driver circuit which drives a light reflecting mirror element is provided on the insulating substrate. The driver circuit substrate is connected to the mirror substrate via a resin layer of a thermosetting adhesive or the like.

Abstract: A driver circuit substrate is prepared and a mirror substrate is so provided as to be placed on the driver circuit substrate. Nine mirror elements are lad out on the mirror substrate in a 3×3 matrix form. The mirror elements are prepared by a microelectromechanical system (MEMS). An insulating substrate is provided on the driver circuit substrate and a driver circuit which drives a light reflecting mirror element is provided on the insulating substrate. The driver circuit substrate is connected to the mirror substrate via a resin layer of a thermosetting adhesive or the like.

Abstract: A driver circuit substrate is prepared and a mirror substrate is so provided as to be placed on the driver circuit substrate. Nine mirror elements are lad out on the mirror substrate in a 3×3 matrix form. The mirror elements are prepared by a microelectromechanical system (MEMS). An insulating substrate is provided on the driver circuit substrate and a driver circuit which drives a light reflecting mirror element is provided on the insulating substrate. The driver circuit substrate is connected to the mirror substrate via a resin layer of a thermosetting adhesive or the like.

Abstract: A gallium nitride type semiconductor laser device includes: a substrate; and a layered structure formed on the substrate. The layered structure at least includes an active layer of a nitride type semiconductor material which is interposed between a pair of nitride type semiconductor layers each functioning as a cladding layer or a guide layer. A current is injected into a stripe region in the layered structure having a width smaller than a width of the active layer. The width of the stripe region is in a range between about 0.2 &mgr;m and about 1.8 &mgr;m.

Abstract: A nitride semiconductor light emitting device includes at least a substrate, an active layer formed of a nitride semiconductor containing mainly In and Ga, a p-electrode and an n-electrode. At least one of the p-electrode and n-electrode is electrically separated into at least two regions.

Abstract: A semiconductor laser device has an active layer which is divided into two regions in the direction of a resonator, i.e., a light-amplifying region and a saturable absorber region. The light-amplifying region and the saturable absorber region are produced to allow the semiconductor laser device to be in a bistable state. For the light-amplifying region and the saturable absorber region respectively, p-electrodes are separately and independently formed. N-electrodes are provided in relation to the p-electrodes. From one of the p-electrodes, a current which is modulated with noise added thereto is injected.

Abstract: A video recording/reproduction system is equipped with a magnetic disk drive, which records and reproduces video data on a magnetic disk by driving a magnetic head. Herein, the magnetic disk drive is controlled by a CPU in accordance with control programs, while a host machine is provided to perform a variety of controls regarding recording and reproduction in accordance with commands being given by manipulation of an operation panel. The magnetic disk drive is characterized by performing a reassignment process and/or calibration such as to suppress reduction of throughput of video data. That is, if the CPU fails to access a target sector of the magnetic disk so that the target sector is regarded as a defect sector, the CPU makes a decision whether to perform the reassignment process based on transfer speeds and vacant capacity of a buffer memory built in the magnetic disk drive.

Abstract: An optical switching subsystem comprising; a plurality of input optical ports for inputting an optical signal, a plurality of output optical ports for outputting the optical signal, an optical switch formed by a micro electromechanical system (MEMS) for switching an optical path among said input optical ports and said output optical ports, a controller for instructing said optical switch to execute switching operation, and self-diagnosis means for measuring performance characteristics of said optical switching subsystem and diagnosing said optical switching subsystem based upon said performance characteristics.

Abstract: A driver circuit substrate is prepared and a mirror substrate is so provided as to be placed on the driver circuit substrate. Nine mirror elements are lad out on the mirror substrate in a 3×3 matrix form. The mirror elements are prepared by a microelectromechanical system (MEMS). An insulating substrate is provided on the driver circuit substrate and a driver circuit which drives a light reflecting mirror element is provided on the insulating substrate. The driver circuit substrate is connected to the mirror substrate via a resin layer of a thermosetting adhesive or the like.

Abstract: A nitride semiconductor laser device having a low threshold current and low noise is provided. The laser device includes n-type and p-type layers made of nitride semiconductor and formed on a substrate, and a light emitting layer between the n-type and p-type layers. The light emitting layer is formed of a well layer or a combination of well and barrier layers. At least the well layer is made of nitride semiconductor containing element X, N and Ga, wherein element is at least one selected from the group consisting of As, P and Sb. The atomic fraction of element X is smaller than that of N. A maximum width through which current is injected into the light emitting layer via the p-type layer is from 1.0 &mgr;m to 4.0 &mgr;m.

Abstract: In a method for making molten metal, reduced metal which is produced in a direct reduction furnace is melted in a melting furnace located in the close vicinity of the direct reduction furnace to produce the molten metal. The method includes the steps of putting the reduced metal into a metallic container, and loading the container containing the reduced metal into the melting furnace. The method may further includes, before the step of loading the container containing the reduced metal into the melting furnace, a step of cooling the surface of the container so that the surface temperature of the container is 500° C. or less.

Abstract: A nitride-type compound semiconductor laser device includes a substrate and a layered structure provided on the substrate. A light absorption layer having a bandgap smaller than a bandgap of an active layer in the layered structure is provided in a position between the cladding layer, which is provided on a side opposite to a mount surface with respect to the active layer, and a surface of the layered structure which is opposite to the mount surface.