Mitsubishi Denki Kabushiki Kaisha

Mitsubishi Electric Corporation

Toshitaka Aoyagi

Kimio Shigihara

Yutaka Nagai

Yasunori Miyazaki

Kazuhisa Takagi

Satoshi Arimoto

Go Sakaino

Yoshito Seiwa

Yoshihito Hirano

Eitaro Ishimura

Keisuke Matsumoto

Masaki Kuzumoto

Tomohiro Akiyama

Shigenori Yagi

Yutaka Mihashi

Takashi Motoda

Akihiro Shima

Katsuhiko Goto

Tsutomu Nagatsuka

Ryuji Ishii

Satoshi Shirai

Yasuhito Myoi

Syoichi Kakimoto

Kazuki Kuba

Kunihiko Isshiki

Tomoko Kadowaki

Takeshi Yamatoya

Hitoshi Watanabe

Masahito Sato

Yoriko Tanigami

An optical waveguide has a semiconductor laser section, an intermediate section, and an optical modulator section on a surface of a substrate. The distance of a surface extending outwardly from and transverse to both sides of a mesa stripe in the semiconductor laser section from the surface of the substrate is larger than the distance of a surface extending outwardly from and transverse to both sides of the mesa stripe in the optical modulator section from the surface of the substrate. The distance of a surface extending outwardly from and transverse to both sides of the mesa stripe in the intermediate section from the surface of the substrate decreases from the semiconductor laser section toward the optical modulator section.

Optical waveguide and semiconductor optical element

Provided is a photodiode array that is capable of outputting an electric signal with a large electric power and an optical microwave transmission system receiver that supplies an electric power with the aid of an optical fiber and does not require the electric power line from the external. An input modulation light is branched and input to a plurality of photodiode elements (), electric output terminals () of the plurality of photodiode elements () are connected in parallel to each other, and a combined electric output is extracted. The electric output terminal () of the photodiode array configured as described above is connected to an antenna () without an intermediation of an amplifier circuit.

Photodiode array configured to increase electrical output power and optical microwave transmission system receiver utilizing the same

An optical wavelength converter includes: a first branch passage and a second branch passage receiving direct current light, one of the first branch passage and the second branch passage receiving input signal light; wavelength converting semiconductor optical amplifiers inserted into the first branch passage and the second branch passage, respectively; and a signal amplifying semiconductor optical amplifier for amplifying the input signal light, which is coupled with a port through which the input signal light is input to one of the first branch passage and the second branch passage. In the optical wavelength converter, differential gain of the signal amplifying semiconductor optical amplifier at a wavelength of the input signal light is less than differential gain of the wavelength converting semiconductor optical amplifier at the wavelength of the direct current light.

Optical wavelength converter

In a refractive index coupling distributed semiconductor laser having a &#x39b;/2-phase-shift distributed feedback structure with a diffraction grating having a refractive index coupling property on an active layer, when viewed in a light distributed feedback direction, a value of (duty of a high refractive index portion)/(duty of a low refractive index portion) of a diffraction grating in a rear end face region is larger than that of a diffraction grating in a front end face region. In this manner, a coupling coefficient &#x3ba;2 in a front end face region of a conventional semiconductor laser is smaller than a coupling coefficient &#x3ba;1 in a rear end face region and is larger than 100 cm.

Semiconductor laser

An n-InP second upper cladding layer is laid on a p-InP lower cladding layer while an active layer having upper and lower boundary surfaces that are uniformly flat in an optical waveguide direction is interposed therebetween. A diffraction layer having a phase-shifted structure in the optical waveguide direction is interposed between the lower cladding layer and the active layer or between the second upper cladding layer and the active layer. The length L of the diffraction grating layer in the direction of the optical waveguide is L&lE;260 &mgr;m; a mean coupling factor &kgr; of a diffraction grating layer is &kgr;&gE;150 cm ; and &kgr;L satisfies 5.6>&kgr;L>3.0.

Semiconductor laser device

An optical module includes a substrate having an upper surface and a groove on the upper surface; an optical fiber having a core and an end facet, disposed in the groove of the substrate; an optical semiconductor device having an upper surface and a light interactive area on the upper surface optically coupled to the optical fiber; and a block having a side surface on which the optical semiconductor device is fixed and a lower surface perpendicular to the side surface. The optical semiconductor device is fixed onto the side surface of the block so that the distance from the light interactive area to the lower surface of the block is equal to the distance from the core of the optical fiber to the upper surface of the substrate; and the block is disposed on the substrate, with the lower surface contacting the upper surface of the substrate, so that the light interactive area is opposed to the end facet of the optical fiber. The core of the optical fiber and the light interactive area are accurately aligned with the surface of the substrate as a reference regardless of the thickness of the substrate, resulting in a high coupling efficiency between the optical fiber and the optical semiconductor device.

Optical module and method of fabricating optical module

A method of manufacturing an optical semiconductor device including forming an optical waveguide on a substrate and forming an alignment mark on the substrate simultaneously with the optical waveguide. The alignment marks do not transmit infrared light and, when the substrate is mounted on an infrared transmissive submount, precise alignment can be achieved by observing transmitted light. Thus, the optical semiconductor device including the substrate is soldered at the desired location.

Method of making optical semi-conductor device

A semiconductor laser chip according to the present invention comprises: a p-type InP substrate; an InGaAsP active layer (optical waveguide) formed on said substrate; a p-n-p InP block layer formed on said substrate; a contact layer formed thereupon; an insulating film formed on said contact layer; a front surface electrode formed on said insulating film; a pair of alignment marks formed at the same time of the optical waveguide; and a back surface electrode formed on said substrate. The alignment marks are formed from the same material, i.e., the same crystal as said optical waveguide. Accordingly, it is possible to improve precision of the relative position between said optical waveguide and said alignment marks.

Optical semiconductor device

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

In an optical modulator including a laser light source emitting laser light and a modulator, a modulation signal source for applying a modulation signal to the modulator, a signal processor for producing and outputting a signal in response to a change in the modulation signal, and a driving current source for generating a driving current applied to the laser light. Wavelength chirping modulation reverse to the wavelength chirping occurring in the modulator is produced in the light emitted from the laser by modulation of the driving current whereby wavelength chirping produced by the modulator is at least partially cancelled and wavelength chirping of the light output from the modulator is reduced.

Optical modulator

A semiconductor device having a semiconductor element and a heat sink radiating heat generated by the semiconductor element incudes an amorphous semiconductor film disposed on the heat sink and the semiconductor element disposed on the amorphous semiconductor film. Therefore, the stress applied to the semiconductor element is reduced because of the amorphous semiconductor film. In one structure, an amorphous semiconductor film comprising amorphous silicon or amorphous germanium is sandwiched between first and second metal films and the semiconductor element is bonded to the second metal film. An ohmic contact is made by alloys formed between the amorphous semiconductor film and the first and second metal films.

Method of manufacturing semi conductor device mounted on a heat sink

A semiconductor optical device includes a semiconductor laser having an effective refractive index n.sub.c, a first film having a refractive index n.sub.1 and a thickness d.sub.1, a second film having a refractive index n.sub.2 and a thickness d.sub.2, and a third film having a refractive index n.sub.3 and a thickness d.sub.3. The first to third films are successively disposed on a facet of the semiconductor laser. In this structure, the refractive indices and thicknesses of the first to third films are determined so that a characteristic matrix Xa of the three films is equal to a characteristic matrix Y of a single film whose refractive index n.sub.f is the square root of the effective refractive index n.sub.c of the semiconductor laser and whose thickness is obtained by dividing an oscillation wavelength .lambda. of the semiconductor laser by 4n.sub.f as represented by the following equation ##EQU1## where .phi.1=2.pi.n.sub.1 d.sub.1 /.lambda., .phi.2=2.pi.n.sub.2 d.sub.2 /.lambda., and .phi.3=2.pi.n.sub.3 d.sub.3 /.lambda.. Therefore, a non-reflection film having no reflectivity at the oscillation wavelength of the semiconductor laser is attained, and the production of the non-reflection film is simplified.

Semiconductor laser structure having a non-reflection film

A semiconductor device having a semiconductor element and a heat sink radiating heat generated by the semiconductor element includes an amorphous semiconductor film disposed on the heat sink and the semiconductor element disposed on the amorphous semiconductor film. Therefore, the stress applied to the semiconductor element is reduced because of the amorphous semiconductor film. In one structure, an amorphous semiconductor film comprising amorphous silicon or amorphous germanium is sandwiched between first and second metal films and the semiconductor element is bonded to the second metal film. An ohmic contact is made by alloys formed between the amorphous semiconductor film and the first and second metal films.

Semiconductor device mounted on a heat sink with an intervening

A semiconductor laser includes a p type cladding layer and an n type cladding layer sandwiching an active layer serially disposed on a semiconductor substrate. The p type cladding layer includes a first dopant impurity producing p type conductivity and a smaller quantity of a second impurity that produces n type conductivity and ionically bonds to the first impurity. The first and second dopant impurities attract each other and cannot move individually during a crystal growth step at high temperature whereby the diffusion of those impurities into the active layer is suppressed, preventing formation of a deep impurity level in the active layer, resulting in a semiconductor laser with a reduced threshold current.

A method for producing a box type quantum well structure includes generating ion clusters, linearly accelerating the clusters with an electric field, passing the accelerated cluster ions through a further field perpendicular to the accelerating direction, causing the cluster ions to follow different ion orbits in accordance with the number of constituent atoms of the respective cluster ions, intercepting the cluster ions having a predetermined number of atoms with a substrate arranged in the orbit of the cluster ions having a predetermined number of atoms. A neutral particle shielding plate is provided along a straight line between the substrate and the cluster ion source to prevent neutral particles from flowing toward the substrate. Thereby, GaAs boxes having the same size can be obtained and variations in the quantum effects of the boxes can be reduced.

Growing community of inventors

Itami, Japan

Toshitaka Aoyagi