Mitsubishi Denki Kabushiki Kaisha

Mitsubishi Electric Corporation

Tohru Takiguchi

Kazuhisa Takagi

Yutaka Mihashi

Katsuhiko Goto

Yoshihiko Hanamaki

Eitaro Ishimura

Toshio Tanaka

Keisuke Matsumoto

Takeshi Saito

Hirotaka Kizuki

Masakazu Takabayashi

Tomoko Kadowaki

Yoshifumi Sasahata

Daisuke Suzuki

Tatsuya Kimura

Kyosuke Kuramoto

Nobuyuki Tomita

Hitoshi Tada

Akira Takemoto

Go Sakaino

Yuichiro Okunuki

Chikara Watatani

Yuji Ohkura

Takushi Itagaki

An optical semiconductor device includes: semiconductor lasers; a wave coupling section multiplexing light output by the semiconductor lasers; an optical amplifying section amplifying output light of the wave coupling section; first optical waveguides respectively optically connecting respective semiconductor lasers to the wave coupling section; a light intensity lowering section located in each of the first optical waveguides and lower light intensity of reflected light that is reflected at a reflecting point located in the optical semiconductor device and that returns to the respective semiconductor lasers; to decrease line width of the light output by the semiconductor lasers.

Optical semiconductor device

An optical semiconductor device includes: semiconductor lasers; a wave coupling section multiplexing light output by the semiconductor lasers; first optical waveguides respectively optically connecting respective semiconductor lasers to the wave coupling section; a phase regulator regulating phase of reflected light that is reflected at a reflecting point located in the optical semiconductor device and that returns to the semiconductor lasers; a second optical waveguide optically connecting the wave coupling section to the phase regulator; an optical amplifying section amplifying output light of the phase regulator; and a third optical waveguide optically connecting an output of the phase regulator to the optical amplifying section. The phase regulator adjusts the phase of reflected light that returns to the semiconductor lasers to decrease line width of the light output by the semiconductor lasers.

An optical semiconductor device includes an optical semiconductor element and an optical waveguide butt-joined to the optical semiconductor element. The optical semiconductor element has a mesa structure including an active layer and a burying layer coating side faces of the active layer. The optical waveguide has a mesa structure including an optical waveguide layer having a layer structure different from the active layer, and a burying layer coating side faces of the optical waveguide layer. Mesa width of the optical waveguide is narrower than mesa width of the optical semiconductor element.

An optical waveguide integrated semiconductor optical device includes a laser and an optical waveguide. The laser includes an active layer and a first cladding layer which are stacked on a second cladding layer. The optical waveguide includes an optical guiding layer and an undoped InP layer which are also stacked on the second cladding layer. A high resistance layer is located between the top surface of the optical guiding layer and a surface of the undoped InP layer and between a side of the first cladding layer and a side of the undoped InP layer.

Optical waveguide integrated semiconductor optical device

A semiconductor laser comprises: a ridge structure including a p-type cladding layer, an active layer, and an n-type cladding layer stacked on one another; and a burying layer burying sides of the ridge structure. The burying layer includes a p-type semiconductor layer and an n-type semiconductor layer that form a pn junction; and one of the p-type semiconductor layer and the n-type semiconductor layer has a carrier concentration of 5&#xd7;10cmor less near the pn junction.

Semiconductor laser

A buried type semiconductor laseris made of a p-type InP substrateand includes a ridge sectionmade up of a p type InP first clad layer, AlGaInAs distorted quantum well active layerand n type InP second clad layerlaminated one atop another. On both sides of the ridge section, an buried current block layermade up of a p-type InP first buried layer, n-type InP second buried layerand semi-insulating Fe-doped InP third buried layerlaminated one atop another is formed. A top face of the third buried layeris covered with an n-type InP semiconductor layer. The above structure can suppress the occurrence of a leakage current path on the top face of the third buried layerand improve reliability of the buried type semiconductor laser.

Buried type semiconductor laser

A semiconductor laser device includes: an electrically insulating film on the top face of a laser chip; and a metal film, on the electrically insulating film. The electrically insulating film and/or the metal film has, in plan, a polygonal shape with five or more apexes, each of the apexes having an interior angle less than 180 degrees. Stress due to a change of temperature during operation is reduced, resulting in a semiconductor laser device having a longer life and higher reliability.

Semiconductor laser device

A semiconductor optical device includes an active layer, a current blocking layer on both sides of the active layer, and a cladding layer on both the active layer and the current blocking layer. The current blocking layer includes a buried layer, at least one intermediate layer of Al(Ga)InAs and a cover blocking layer. The cover blocking layer is located between the cladding layer and the Al(Ga)InAs layers and has a higher oxidation resistance than the Al(Ga)InAs layer. The current blocking layer is grown such that each Al(Ga)InAs layer is not exposed at the surface of the current blocking layer.

Semiconductor optical device having an improved current blocking layer and manufacturing method thereof

A ridge waveguide semiconductor laser includes an active layer, semiconductor layers on the active layer and having a ridge-shaped waveguide, an insulating film on the semiconductor layer, a first electrode layer in contact with the semiconductor layer through an opening in the insulating film, and a second electrode layer on the first electrode layer having a stripe shape and extending along the waveguide. A distance from an end face of a resonator of the laser to an edge of the second electrode layer does not exceed 20 &#x3bc;m.

Ridge waveguide semiconductor laser

A laser device includes a double hetero-structure element constructed by depositing a p-type cladding layer, a quantum well active layer, an n-type thin first cladding layer and an n-type thick second cladding layer sequentially. A ridge-waveguide is shaped between two trenches formed in the second cladding layer. The first cladding layer serves as an etching stopper while etching the second cladding layer to form the two trenches. The trenches reach to or reach in vicinity to the surface of the first cladding layer. High-resistance regions may be formed in portions of the first cladding layer directly underneath the trenches. The thin first cladding layer, suppresses leakage current and improves the temperature characteristics and the operating speed characteristics of the laser device.

Ridge-waveguide semiconductor laser device

A ridge waveguide distributed feedback laser includes a p-type InGaAsP grating layer having a p-type carrier density ranging from 1.5&times;10 cm to 4.0&times;10 cm and preferably from 2.0&times;10 cm to 3.0&times;10 cm . In combination with such raised levels of p-type carrier density in the InGaAsP grating layer, the p-type carrier density may also be enhanced both in a p-type InP layer between the grating layer and a contact layer, and in another p-type InP layer between the grating layer and a quantum well active layer, the density ranging from 1.5&times;10 cm to 4.0&times;10 cm and preferably from 2.0&times;10 cm to 3.0&times;10 cm .

Ridge waveguide distributed feedback laser

A distributed feedback laser device includes a semiconductor base having a ridge waveguide structure projecting from its principal plane. The ridge waveguide structure extends with a predetermined width from one edge of the semiconductor base to an opposite edge. A diffraction grating layer is confined within the ridge structure. The ridge waveguide structure is formed by etching using an SiO film and a resist film as masks so that the diffraction grating layer is produced with substantially the same width as, or a less width than, the width of the ridge waveguide structure. A &lgr;/4 shift diffraction grating or a chirped diffraction grating is preferably employed.

Distributed feedback laser device and method for manufacturing the same

On a laminate containing a p-InGaAsP layer, one of layers including a diffraction grating layer, an SiO insulating film pattern that has first rectangular openings, each opening having a long side orthogonal with the direction of the optical wave guide, periodically arranged at intervals in the direction of the optical wave guide is formed. An SiN insulating film pattern having a second opening with a strip shape having a width narrower than the long side of the first opening, extending in the direction of the optical wave guide, is formed on the SiO insulating film pattern. The laminate containing the p-InGaAsP layer is dry-etched using the SiO insulating film pattern and the SiN insulating film pattern as masks, and methane and a hydrogen plasma as the etching media.

Method for manufacturing semiconductor laser device

A ridge waveguide semiconductor laser that is excellent in optical output characteristic and high-frequency characteristic is provided. A p-type InP cladding layer having a ridge shape is formed over a p-type AlInAs cladding layer via a p-type InP layer and a p-type GaInAsP etching stopper layer, thereby suppressing the increase in the series resistance due to discontinuous band structure between an etching stopper layer and the AlGaInAs cladding layer and reducing the threshold current of the laser. Also the InP cladding layer is formed in a ridge shape with the portion near the base thereof being splayed like a skirt, thereby keeping the p-type metal electrode from the light emitting region and suppressing the absorption loss of light due to the p-type metal electrode. Further, by increasing the resistance of the active layers in the region that interposes a main current path, parasitic capacitance formed by the active layer in the region where current does not flow can be decreased thereby improving the high-frequency characteristic of the laser.

Semiconductor laser element

An electrode for a semiconductor device includes a gold-containing thin film and a gold-containing plated film on the thin film. The plated film covers the entire thin film. No open surface is present between the thin gold film and the gold plating so no excessive current concentration occurs in any area.

Growing community of inventors

Tokyo, Japan

Tohru Takiguchi