Mitsubishi Denki Kabushiki Kaisha

Mitsubishi Electric Corporation

Akihiro Shima

Yutaka Nagai

Takeshi Miura

Norio Hayafuji

Motoharu Miyashita

Harumi Nishiguchi

Wataru Susaki

Kunihiko Isshiki

Tomoko Kadowaki

Nobuo Takeshita

Shigenori Yagi

Tetsuya Yagi

Toshitaka Aoyagi

Takahiko Fujisaka

Masahisa Shinoda

Shoichi Karakida

Zempei Kawazu

Akira Ishimori

Yuji Ohkura

Morihiro Karaki

Yasutomo Kajikawa

Yoshimasa Ohashi

Mitsuru Irie

Naoyuki Egusa

Manabu Koike

Yasuyuki Satou

Koji Aono

Yoshihisa Tashiro

Takeshi Utakouji

Yoriko Tanigami

A display and illumination system includes a light source section accommodating a light source; an optical fiber for transmitting light from the light source; a display illumination unit radiating light transmitted by the optical fiber; a light source module installed in the light source section, accommodating the light source, and optically connected to the optical fiber; a plug electrode installed in the light source module and supplying electric power to the light source; a convex portion on a first side of the light source module, engaging the optical fiber, and extracting light from the light source; and a concave portion located opposite the first side of the light source module and urging the convex portion toward the optical fiber with a constant force.

Display and illumination system

In fabricating a semiconductor laser producing light with a wavelength of 770 to 810 nm, impurities are introduced into an MQW active layer near a light emitting facet of the laser to form a disordered region constituting a window layer. Pump light is applied to the window layer to generate photoluminescence whose wavelength &#x3bb; dpl (nm) is measured. A blue shift amount &#x3bb; bl (nm) is defined as the difference between the wavelength &#x3bb; apl (nm) 0f photoluminescence generated by application of pump light to the active layer on the one hand, and the wavelength &#x3bb; dpl (nm) of photoluminescence from the window layer under pump light irradiation on the other hand. The blue shift amount &#x3bb; bl is referenced during the fabrication process in order to predict catastrophic optical damage levels of semiconductor lasers.

Method of fabricating semiconductor laser

A forward mesa ridge-embedded semiconductor laser device provides a high power output and includes a base portion of a forward mesa ridge having a narrow width to stabilize transverse mode oscillation and an upper cladding layer having a thickness sufficient to reduce loss of the laser beam, a top portion of the forward mesa ridge being interposed between parts of the current blocking layer to reduce the device resistance. The upper cladding layer includes a first cladding layer having the forward mesa ridge and a second cladding layer opposite the first cladding layer. The second cladding layer is deposited over the first cladding layer through the forward mesa ridge and a current blocking layer is positioned on both sides of the forward mesa ridge.

Semiconductor laser device and process for manufacturing the same

A semiconductor laser includes a first conductivity type semiconductor substrate, a first conductivity type lower cladding layer, a quantum well structure active layer including alternately laminated barrier and well layers, a disordered region extending to laser resonator facets, a second conductivity type first upper cladding layer disposed on the quantum well structure active layer, a ridge structure disposed on the first cladding layer, and having a first region not proximate the laser resonator facets including a second conductivity type second upper cladding layer and a second conductivity type first contact layer and a second region, proximate a laser resonator facet having a first conductivity type first semiconductor layer of the same material and thickness as the second upper cladding layer and a first conductivity type second semiconductor layer of same material as the first contact layer, a first conductivity type current blocking layer having a band gap energy larger than that of the second upper cladding burying the ridge structure, and a second conductivity type second contact layer disposed on the current blocking layer and the ridge structure. The band gap energy at the laser resonator facets is larger than in other regions and serves as a window structure. A refractive index distribution in the transverse direction confines laser light in the transverse direction below the ridge structure and there is no astigmatism.

Semiconductor laser

A semiconductor device includes a semiconductor substrate, a strained multi-quantum well with alternatingly laminated first barrier layers and well layers with second barrier layers as outermost layers of the strained MQW structure. The strained MQW structure has a safety factor K.sub.safe =3.9; and ##EQU1## Therefore, it is possible to make the strained MQW structure have a sufficient margin with respect to critical conditions concerning the generation of dislocations, and deterioration of operational characteristics in continuous operation of the semiconductor device can be suppressed so that the reliability of the semiconductor device is enhanced.

Semiconductor device and fabricating method thereof

A semiconductor laser device includes: a substrate serving as a heat sink; a thermal buffer plate disposed on the surface of the substrate; a first semiconductor laser chip having first and second main surfaces and including a first light emitting point in the vicinity of the first main surface, the first semiconductor laser chip being disposed on the surface of the thermal buffer plate at the second main surface; spaced apart thermal conductors disposed on the first main surface of the first semiconductor laser chip spaced from the first light emitting point with the first light emitting point between them; a second semiconductor laser chip having third and fourth main surfaces and including a second light emitting point in the vicinity of the third main surface, the second semiconductor laser chip being disposed on the thermal conductors at the third main surface so that the light radiation direction of the second semiconductor laser chip is parallel to the light radiation direction of the first semiconductor laser chip, wherein the second light emitting point is opposed to and close to the first emitting point. Even when the environmental temperature changes, the expansion and contraction of the interval between the light emitting points is smaller than in prior art structures.

Semiconductor laser device and optical disc apparatus provided with the

A semiconductor laser includes a compound semiconductor substrate of a first conductivity type; successively disposed on said semiconductor substrate, a first conductivity type lower cladding layer, an active layer including a multiple quantum well structure, first and second upper cladding layers of a second conductivity type opposite the first conductivity type, and a first contacting layer of the second conductivity type in electrical contact with the second upper cladding layer; first and second electrodes in electrical contact with the semiconductor substrate and the first contacting layer, respectively, the semiconductor laser including opposed facets transverse to the lower cladding and the first and second upper cladding layers, the second upper cladding layer having a ridge shape that extends between the facets of the semiconductor laser and is centrally disposed on the first upper cladding layer; a first conductivity type current blocking layer disposed on and between the first upper cladding layer and the first contacting layer, contacting opposite sides of the ridge, and extending between the facets; and a window structure contiguous with each of the facets, each window structure comprising a region including a dopant impurity, each region being disposed within parts of the lower cladding layer, the active layer, and the first upper cladding layer opposite the ridge but not extending substantially into the second upper cladding layer, the multiple quantum well structure of the active layer being disordered in each window region.

Semiconductor laser with improved window structure

A semiconductor laser includes a first conductivity type semiconductor substrate having opposite first and second surfaces, a first conductivity type semiconductor layer grown on the first surface, a thin GaInP or AlGaInP active layer having a band gap energy smaller than that of the first conductivity type semiconductor layer, and a second conductivity type semiconductor layer having a band gap energy larger than that of the active layer. The first conductivity type semiconductor layer has a first crystal plane that provides a quantum wire structure of the active layer and second crystal planes disposed at opposite sides of the first crystal plane. The first crystal plane forms a first angle smaller than a prescribed angle with a {100} surface, and the second crystal plane forms a second angle larger than the first angle with the {100} surface. The active layer is grown under growth conditions that produce atoms ordered opposite {100} surface and provide the active layer in a disordering state wherein atoms opposite a surface forming an angle with the {100} surface. Therefore, a semiconductor laser including a quantum wire with improved quantum effect is realized.

Semiconductor laser and method of producing the semiconductor laser

The second harmonic wave of a solid laser light which is emitted from a second harmonic wave light source is divided into a plurality of laser beams by a diffraction grating. The divided laser beams are converged on a record carrier into a plurality of light spots by an optical head. Magnetic field generating coils for applying magnetic fields to the respective light spots in accordance with the recording signals from a signal line are disposed under the record carrier. Part of the solid laser light is reflected and input to a beam splitter. Since part of the light input to the beam splitter is taken out, a stabilizer controls the output of the solid laser light from the second harmonic wave light source, parallel recording/reproduction using the plurality of light spots which are arranged on the record carrier is enabled and the formation of the plurality of light spots is effectively controlled. Thus, a magneto-optical recording and reproducing apparatus which is capable of high-density recording and high-speed data transfer, which supplies a stable and accurate optical output, and which facilitates the control of the optical output is provided.

Magneto-optical recording and reproducing apparatus

A semiconductor laser includes: a first conductivity type semiconductor substrate; a first conductivity type lower cladding layer disposed on the substrate; a quantum well structure disposed on the lower cladding layer; a second conductivity type upper cladding disposed on the quantum well structure; a ridge including a stripe-shaped second conductivity type semiconductor of a length extending in the laser resonator length direction reaching neither semiconductor laser facet and disposed on the upper cladding layer; disordered regions, i.e, window structures, formed in the quantum well structure in the vicinity of the laser resonator facets by ion-implanting a dopant impurity; and a first conductivity type current blocking layer, disposed on the upper cladding layer on the disordered quantum well structure layer, burying the ridge. Accordingly, in the window structure regions, flow of a current that does not produce laser light is prevented, resulting in a semiconductor laser having a high power light output, a low threshold current, and a low operational current.

Semiconductor laser with COD preventing disordered regions

In accordance with the invention, after a crystal growth is carried out successively to produce at least a first conductivity type lower cladding layer, an active layer, a second conductivity type first upper cladding layer of AlGaAs having an AlAs composition ratio of 0.38 to 0.6, an etching stopper layer of AlGaAs having an AlAs composition ratio of more than 0.6, and a second conductivity type second upper cladding layer of AlGaAs having an AlAs composition ratio of 0.38 to 0.6, the second upper cladding layer is selectively etched using an etchant including an organic acid and hydrogen peroxide, thereby forming a ridge. As a result, a ridge-type semiconductor laser device which has a desirable laser structure and an oscillation wavelength below 830 nm can be produced easily with improved controllability and reproducibility.

Method for producing semiconductor laser device using etch stop layer

In accordance with the invention, after a crystal growth is carried out successively to produce at least a first conductivity type lower cladding layer, and active layer, a second conductivity type first upper cladding layer of AlGaAs having an AlAs composition ratio of 0.38 to 0.6, an etching stopper layer of AlGaAs having an AlAs composition ratio of more than 0.6, and a second conductivity type second upper cladding layer of AlGaAs having an AlAs composition ratio of 0.38 to 0.6, the second upper cladding layer is selectively etched using an etchant including an organic acid and hydrogen peroxide, thereby forming a ridge. As a result, a ridge-type semiconductor laser device which has a desirable laser structure and an oscillation wavelength below 830 nm can be produced easily with improved controllability and reproducibility.

Semiconductor laser including an aluminum-rich AlGaAs etch stopping layer

A double heterojunction semiconductor laser according to the invention includes first and third cladding layers sandwiching an active layer. The third cladding layer includes a mesa opposite a light emitting region of the active layer. The mesa is confined by a current blocking layer. A cap layer that is part of the mesa is used as a dopant diffusion source to dope a light emitting region of the active layer heavily. A second cladding layer may be present between the active layer and third cladding layer having the same conductivity type as the third cladding layer adjacent the light emitting region but the opposite conductivity type elsewhere. A semiconductor laser according to the invention may also include a stripe groove structure. The semiconductor lasers include pnpn structures outside the light emitting region and in window structures adjacent the facets of the semiconductor laser for suppressing leakage currents, thereby increasing laser efficiency and reducing threshold current while increasing power output.

A pulsed doppler radar system having an improved detection probability, comprising an antenna unit, a transmitter for transmitting a signal through the antenna unit, a receiver for receiving a signal reflected by a target through the antenna unit to provide a reception signal. A processing unit which receives the reception signal from the receiver determines, in accordance with a range of the target and a signal-to-noise ratio and bandwidth of the reception signal, an optimum integration number which maximizes the detection probability and performs coherent integration on the reception signal by the number of times equal to the determined optimum integration number thereby outputting a signal having a predetermined level. Such a signal is fed to a display and an image of the target is displayed on a display.

Growing community of inventors

Itami, Japan

Akihiro Shima