Nec Corporation

Renesas Electronics Corporation

Nec Electronics Corporation

Tetsuro Okuda

Hirohito Yamada

Toshitaka Torikai

Isao Watanabe

Masahide Kobayashi

Kazuo Fukagai

Kenji Endo

Kentaro Tada

Satoshi Ae

Shoutarou Kitamura

Suguru Kato

To improve characteristics of a semiconductor device (semiconductor laser), an active layer waveguide (AWG) comprised of InP is formed over an exposed part of a surface of a substrate having an off angle ranging from 0.5&#xb0; to 1.0&#xb0; in a [1-1-1] direction from a (100) plane to extend in the [0-1-1] direction. A cover layer comprised of p-type InP is formed over the AWG with a V/III ratio of 2000 or more. Thereby, it is possible to obtain excellent multiple quantum wells (MQWs) by reducing a film thickness variation of the AWG. Moreover, the cover layer having side faces where a (0-11) plane almost perpendicular to a substrate surface mainly appears can be formed. A sectional shape of a lamination part of the cover layer and the AWG becomes an approximately rectangular shape. Therefore, an electrification region can be enlarged and it is possible to reduce a resistance of the semiconductor device.

Method for manufacturing semiconductor device and semiconductor device

In a semiconductor laser, a block layer is provided on both sides of a mesa-type semiconductor part having an n-type cladding layer, an active layer, and a p-type cladding layer. The block layer has: a p-type block layer formed on the side surface of the mesa-type semiconductor part and over a p-type semiconductor substrate; a high-resistance layer formed over the p-type block layer; and an n-type block layer formed over the high-resistance layer, which has a higher resistance than that of the p-type block layer. By providing the high-resistance layer between the p-type block layer and the n-type block layer, the thickness of the p-type block layer can be controlled and a leakage current (flow of a hole) can be reduced. Further, the distance between the n-type cladding layer and the n-type block layer can be secured, and hence a leakage current (flow of an electron) can be prevented.

Semiconductor laser and manufacturing method thereof

Provided is a semiconductor laser, wherein (&#x3bb;a&#x2212;&#x3bb;w)&#x3e;15 (nm) and Lt&#x3c;25 (&#x3bc;m), where &#x3bb;w is the wavelength of light corresponding to the band gap of the active layer disposed at a position within a distance of 2 &#x3bc;m from one end surface in a resonator direction, &#x3bb;a is the wavelength of light corresponding to the band gap of the active layer disposed at a position that is spaced a distance of equal to or more than ( 3/10)L and &#x2266;( 7/10)L from the one end surface in a resonator direction, 'L' is the resonator length, and 'Lt' is the length of a transition region provided between the position of the active layer with a band gap corresponding to a light wavelength of &#x3bb;w+2 (nm) and the position of the active layer with a band gap corresponding to a light wavelength of &#x3bb;a&#x2212;2 (nm) in the resonator direction.

Method of manufacturing a semiconductor laser

Provided is a semiconductor laser, wherein (&#x3bb;a&#x2212;&#x3bb;w)&#x3e;15 (nm) and Lt&#x3c;25 (&#x3bc;m), where &#x3bb;w is the wavelength of light corresponding to the band gap of the active layer disposed at a position within a distance of 2 &#x3bc;m from one end surface in a resonator direction, &#x3bb;a is the wavelength of light corresponding to the band gap of the active layer disposed at a position that is spaced a distance of equal to or more than ( 3/10)L and &#x3c;( 7/10)L from the one end surface in a resonator direction, 'L' is the resonator length, and 'Lt' is the length of a transition region provided between the position of the active layer with a band gap corresponding to a light wavelength of &#x3bb;w+2 (nm) and the position of the active layer with a band gap corresponding to a light wavelength of &#x3bb;a&#x2212;2 (nm) in the resonator direction.

Semiconductor laser and method of manufacturing semiconductor laser

There is provided a semiconductor laser comprising an n-InP substrate; a multilayer film including a strained MQW active layeron the n-InP substrate

Semiconductor laser and manufacturing process therefor

In a distributed feedback semiconductor laser having at least an active layer and a diffraction grating on a semiconductor substrate and so constructed that a current is injected uniformly over an axial direction of a resonator, a bandgap wavelength of the active layer in the neighborhood of a light outputting end or a backward end opposite to the light outputting end, is shorter than that in the other region of the active layer along the axial direction of the resonator.

Distributed feedback semiconductor laser

A distributed feedback laser device comprises an optical waveguide having one end facet serving as a beam emission surface and the other end facet serving as a reflection surface, an active layer formed between the beam emission surface and the reflection surface, and a diffraction grating formed so as to extend along the active layer in the optical waveguide. The active layer has a first region located nearer to the beam emission surface than to the reflection surface and a second region located nearer to the reflection surface than to the beam emission surface. The first region is narrower in width than the second region. The diffraction grating has first and second portions located along the first and the second regions, respectively. The first portion is longer in pitch than the second portion.

Distributed feedback laser device high in coupling efficiency with optical fiber

A dopant such as Si is introduced to recombination layers,The Si concentration is about 1&times;10,to 5&times;10,cm,. Thus, a carrier lifetime in the recombination layers,may be reduced to relatively increase a leakage current flowing the recombination layers,while relatively reducing a leakage current flowing channels

Semiconductor laser and a method of manufacturing therefor

In a semiconductor laser for analog modulation, intermodulation distortion at high temperatures and/or at high outputs is reduced. In a DC-PBH semiconductor laser, the width (Wm) of the electrode mesa 11 is set at 10 .mu.m or less, and the width of each recombination layer 2 is set at 0.1 .mu.m or more. Further, the distance between one end of the active layer 1 and one end of each current-blocking layer 5 is set at 0.01 .mu.m to 0.5 .mu.m.

Semiconductor laser and process for production thereof

The present invention provides a grating structure partially provided in a semiconductor laser device having a first facet of a first reflectivity and a second facet of a second reflectivity which is larger than the first reflectivity. The grating structure extends within a half area near the first facet in the semiconductor laser device. The grating structure has a grating length in a cavity direction of not more than one third of a cavity length defined as a distance between the first and second facets. The grating structure has an integrated coupling coefficient value in the range of 0.4-0.6, the integrated coupling coefficient value is obtained by integrating coupling coefficient of the grating structure with positions in the cavity direction.

Distributed feed back laser with a grating structure adjusted for a

In a laser diode element including a front facet, a rear facet, a laser cavity formed between the front the rear facets and which has a predetermined length L, coating layers coated on the front facet to provide a reflectivity smaller than 5%, and an active layer and a uniform grating having regular corrugation formed in the direction of the laser cavity and which are coupled to each other at a predetermined coupling constant K, the laser diode element is specified by a product of the predetermined coupling constant and the predetermined length L and falling within a range between 0.4 and 1.0, both inclusive.

Laser diode element with excellent intermodulation distortion

In a laser diode element including a front facet, a rear facet, a laser cavity formed between the front rear facets and which has a predetermined length L, coating layers coated on the front facet to provide a reflectivity smaller than 5%, and an active layer and a uniform grating having regular corrugation formed in the direction of the layer cavity and which are coupled to each other at a predetermined coupling constant K, the laser diode element is specified by a product of the predetermined coupling constant and the predetermined length L and falling within a range between 0.4 and 1.0, both inclusive.

A semiconductor distributed feedback laser emitting device has upper electrodes arranged in a longitudinal direction of an oscillator for supplying current to the oscillator, and a separating electrode is provided between the upper electrodes for making the distribution of an electric field strength in the longitudinal direction uniform by changing the current density in the separating electrode with respect to the current density in the upper electrodes, thereby improving a second intermodulation distortion.

Semiconductor distributed feedback laser emitting device improved in

A distributed-feedback laser has a diffractive grating, an optical waveguide layer, and an active region. The optical waveguide layer has equivalent refractive indexes larger towards cavity end facets and smaller towards a device center portion along a cavity. The active region containing the optical waveguide layer has widths wider towards the cavity end facets and narrower towards the device center portion along the cavity. The optical waveguide layer has a uniform electric intensity distribution along the cavity to improve the linearity of current versus optical output characteristics. In another arrangement, the optical waveguide layer formed on the diffractive grating has in its compositions longer wavelengths towards the cavity end facets and shorter wavelengths towards the cavity center portion along the cavity, whereby the optical waveguide layer has a uniform optical intensity distribution along the cavity to improve the linearity of current versus optical output characteristics. The distributed-feedback laser provided is with improved analog modulation distortion characteristics.

Growing community of inventors

Kanagawa, Japan

Tetsuro Okuda