Nec Corporation

Nippon Electric Co., Ltd.

Nippon Telegraph and Telephone Public Corporation

Ikuo Mito

Kohroh Kobayashi

Tatsuya Sasaki

Mitsuhiro Kitamura

Masayuki Yamaguchi

Keiro Komatsu

Kazuhisa Kaede

Shigeo Matsushita

Takeshi Takeuchi

Tomoaki Kato

Yoshihiko Suemura

Kiichi Hamamoto

Katsumi Emura

Kenko Taguchi

Tomoo Yanase

Shigetoki Sugimoto

Ro Ishikawa

Masako Hayashi

Tetsuhiko Ikegami

Tomoaki Katoh

A semiconductor waveguide layer is provided in an optical semiconductor integrated circuit device comprising a passive region having at least a branch and an active region having at least a laser diode connected to the branch and at least a photo-diode connected to the branch. The active region is in contact with the passive region. The waveguide layer selectively extends over the passive region and the active region. The semiconductor waveguide layer in the active region has a wavelength composition larger than that in the passive region. The waveguide layer has a semiconductor crystal structure which is continuous not only over the active and passive regions but also at a boundary between the active and passive regions.

Optical integrated circuit and method for fabricating the same

There is to provide a method of producing efficiently a custom IC optical integrated circuit with convenient connections between tile optical devices with less loss of the light and with different connection but similar configuration. The optical integrated circuit is comprised of a plurality of ridge-type active optical devices formed of a variable wavelength laser section and a light modulator and a ridge-type passive optical waveguide of a Y-branching optical waveguide for connecting between the ridge-type active optical devices with each other or for connecting the plural ridge-type active optical devices with output waveguides, and ridge sections of the ridge-type active optical device and the ridge-type passive optical waveguide are formed by the selective crystal growth.

Method of producing optical integrated circuit

In order to induce a flat frequency modulation response in a multi-electrode semiconductor laser which includes an active region and at least one phase control region with no active layer, a modulation current is applied to both of the active region and the phase control region. Further, an improved electrode arrangement for inducing a flat frequency modulation response in a multi-electrode semiconductor laser is present. The semiconductor laser includes three regions: an active region, a phase control region and a Bragg reflector region. Each of the active region, the phase control region and the Bragg reflector region being provided with an electrode for receiving an injection current, wherein the electrode provided for the active layer extends into the phase control region.

Method and electrode arrangement for inducing flat frequency modulation

A method for fabricating an optical semiconductor device includes the steps of forming at least two stripes of dielectric parallel to each other with a predetermined interval on a semiconductor substrate, growing a crystal selectively between the two stripes, and forming a multi-layer structure which is required to have a width determined by the crystal grown between the two stripes. In such a method, the width of the multi-layer structure including an active layer or a waveguide is controlled precisely, because there is no step of etching a semiconductor layer, so that the characteristics of the device may improve and the yield may increase.

Method for fabricating an optical semiconductor device

A bistable distributed feedback laser device is employed for transmitting optical signals. A bias current which is less than the threshold lasing turnoff current is supplied to the laser. A drive circuit provides a pulse current which, when added to the bias current, exceeds the threshold lasing turnon current. In this manner, the device is modulated so as to traverse the hysteresis region, hereby preventing undesirable expansion of the spectrum line width.

Optical transmitter utilizing a bistable distributed feedback

In a distributed feedback laser diode comprising an optical waveguide layer, a first stack of a current confining and a current blocking layer, and a second stack of a first cladding layer, an active layer, and a second cladding layer consecutively on a semiconductor substrate having a corrugated surface, a pair of inwardly directed surfaces is formed to define a groove in the first stack, to divide the current blocking layer into two current blocking parts, and to expose an area of the waveguide layer as a groove bottom. The first cladding layer is formed on the current blocking parts, the inwardly directed surfaces, and the groove bottom. The laser diode is suitable to manufacture by metal organic chemical vapor deposition. The groove is preferably perpendicular to corrugations of the corrugated surface. The groove bottom may have a width of 1.5 microns. The groove can be formed by chemical etching of the first stack before epitaxial growth of the first cladding layer.

Distributed feedback laser diode comprising an active layer partly

An improved distributed feedback laser diode comprises a diffraction grating in a resonator. The diffraction grating is formed to have a phase shift of .lambda./8 to 3.lambda./16 at a portion thereof so that the phase shift amount of approximately .lambda./4 is obtained in a case where a maximum rate of light output is produced thereby to result in a single axial mode oscillation.

Distributed feedback laser diode

Laser chips which are stably operated in a single mode result from a semiconductor laser device in which a diffraction grating is formed neighboring an active layer. The distribution of current to be injected into the active layer is controlled to a configuration which substantially corresponds to that of the distribution of the field intensity of light along the laser optical axis inside the active layer.

Distributed feedback semiconductor laser device

A tunable semiconductor laser device includes a laser region and a tuning region, with a highly reflective surface formed on the cleaved vertical end facet of the tuning region for providing a reflectivity of 50% or more. The laser and tuning regions are formed on a common semiconductor substrate with the laser region having an active layer formed over the substrate, an optical waveguide layer adjacent the active layer and an electrode for carrying a drive current to the active region. The tuning region, adjacent the laser region on the substrate includes an optical waveguide which extends from the optical waveguide of the laser region, and a tuning current carrying electrode for injecting a tuning current across the waveguide layer of the tuning region. The tuning current alters the refractive index of the waveguide layer interface which changes the phase of the tuning region. Changing the tuning current varies the laser wavelength. The highly reflective end facet assures continuous wavelength tuning. The laser device may be incorporated into an integrated optical local oscillator comprising the laser device, a photodiode, a branched optical waveguide including an input port for mixing the output of the laser device and the light from the input port before being received by the photodiode.

Semiconductor laser device

A method of growing an InGaAsP layer on a corrugated InP substrate as a part of a procedure for producing a DFB semiconductor laser includes the step of heating the substrate up to temperatures approaching 700.degree. C. while holding the substrate in an atmosphere which contains arsine and phosphine. The substrate is subsequently moved to InGaAsP and InP growth chambers for growth of these respective layers. The method of the invention is advantageous in that the corrugated structure of the substrate is maintained intact throughout the procedure.

Method of growing InGaAsP on InP substrate with corrugation

A single longitudinal mode semiconductor laser having a distributed Bragg reflector with increased diffractive efficiency. The increased diffractive efficiency results from placing the diffraction grating within the optical waveguide, rather than on either its upper or its lower face. This placement enables maximization of the electric field component of light beams subjected to periodic variations in the refractive index within the optical waveguide, in turn enabling increased reflecting power which results in a low oscillation threshold and a high differential quantum efficiency.

Single longitudinal mode semiconductor laser

A single longitudinal mode semiconductor laser is fabricated as a composite structure using the plane orientation dependency of the growth rate to grow epitaxial layers which are separate on both sides of a step having a slant crystal face, thus forming a first level and a second level higher than the first level, the step defining the transition between the first and second levels, which transistion is in the propagation direction of the laser radiation. A first semiconductor layer having a periodic structure and forming a waveguide layer extending over the second level. A second semiconductor layer separated at the step has a first portion extending over the first semiconductor layer and a second portion over the first level. A semiconductor active layer also separated at the step extends over both portions of the second semiconductor layer such that an end of the semiconductor active layer abuts an end of the waveguide layer at the step.

Double heterostructure semiconductor laser with periodic structure

A double-channel planar buried-heterostructure semiconductor laser diode (DC-PBH LD) has improved high frequency response characteristics due to lower p-n junction capacitance resulting from the interposition of a low carrier concentration blocking layer between p-n-p-n blocking layers of the DC-PBH LD structure.

Double-channel planar heterostructure semiconductor laser

A double heterostructure semiconductor laser device has a first wide bandgap layer, forming an optical guide layer, a portion of which is provided with periodic corrugations to form a distributed Bragg reflector. The optical guide layer extends along a major surface of the substrate in the direction of laser propagation. A narrow bandgap active region over which is disposed a second wide bandgap region, forming a first cladding layer, are both disposed over a portion of the optical guide layer in the direction of laser propagation to produce an amplifier section. The remaining portion of the optical guide layer in the direction of laser propagation is disposed over that portion of the substrate containing the distributed Bragg reflector to thereby form a reflector section. First and second channels are formed in said device in the direction of laser propagation to produce a mesa, with additional cladding layers, forming current blocking layers, being disposed in said channels but not over the mesa, to electrically isolate said mesa.

Double channel planar buried heterostructure laser with periodic

A process for epitaxial growth which effects epitaxial growth while suppressing thermal deformation of surface corrugations of an InGaAsP/InP system semiconductor substrate. Deformation of surface corrugations is suppressed by disposing a GaAs.sub.1-z P.sub.z (0.1.ltoreq.z.ltoreq.0.8) wafer over and in close contact with the surface of the semiconductor substrate until immediately before a start of the epitaxial growth process.

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Tokyo, Japan

Ikuo Mito