Eudyna Devices Inc.

Fujitsu Corporation

Tsutomu Ishikawa

Hirohiko Kobayashi

Hirokazu Tanaka

Takuya Fujii

Hajime Shoji

Toyotoshi Machida

Tsuyoshi Yamamoto

Kazumasa Takabayashi

Norihiko Sekine

Hajime Shoij

An optical semiconductor device has a semiconductor substrate, an optical semiconductor region and a heater. The optical semiconductor region is provided on the semiconductor substrate and has a width smaller than that of the semiconductor substrate. The heater is provided on the optical semiconductor region. The optical semiconductor region has a cladding region, an optical waveguide layer and a low thermal conductivity layer. The optical waveguide layer is provided in the cladding region and has a refractive index higher than that of the cladding region. The low thermal conductivity layer is provided between the optical waveguide layer and the semiconductor substrate and has a thermal conductivity lower than that of the cladding region.

Optical semiconductor device, laser chip and laser module

An optical semiconductor device has a semiconductor substrate, a semiconductor region and heater. The semiconductor region has a stripe shape demarcated with a top face and a side face thereof. The stripe shape has a width smaller than a width of the semiconductor substrate. An optical waveguide layer is located in the semiconductor region. A distance from a lower end of the side face of the semiconductor region to the optical waveguide layer is more than half of the width of the semiconductor region. The heater is provided above the optical waveguide layer.

Semiconductor laser with heater

A tunable laser module includes a tunable laser section including a gain medium and a wavelength filter having a periodic characteristic which brings about a discontinuous variation of an oscillation wavelength, and a monitoring section adapted to output a monitoring signal which periodically varies in response to the oscillation wavelength of the tunable laser section. The monitoring section includes a monitoring wavelength filter having a periodic characteristic which defines the monitoring signal. The relationship between the period of the wavelength filter and the period of the monitoring wavelength filter is set such that the monitoring signal varies when the oscillation wavelength varies discontinuously.

Tunable laser module, tunable laser apparatus and controlling method for tunable laser

A testing method of a wavelength-tunable laser having a resonator including wavelength selection portions having wavelength property different from each other includes a first step of controlling the wavelength-tunable laser so as to oscillate at a given wavelength according to an initial setting value, a second step of tuning the wavelength property of the wavelength selection portions and detecting discontinuity point of gain-condition-changing of the wavelength-tunable laser, and a third step of obtaining a stable operating point of the wavelength selection portion according to a limiting point of an oscillation condition at the given wavelength, the limiting point being a point when the discontinuity point is detected.

Testing method of wavelength-tunable laser, controlling method of wavelength-tunable laser and laser device

A method of controlling a semiconductor laser that has a plurality of wavelength selection portions having a different wavelength property from each other and is mounted on a temperature control device, including: a first step of correcting a temperature of the temperature control device according to a detected output wavelength of the semiconductor laser; and a second step of controlling at least one of the wavelength selection portions so that changing amount differentials between each wavelength property of the plurality of the wavelength selection portions is reduced, the changing amount differential being caused by correcting the temperature of the temperature control device.

Method of controlling semiconductor laser

An optical device includes an optical element, a detector and a controller. The optical element has an optical waveguide. Refractive index of the optical waveguide is controlled by a heater. A temperature of the optical element is controlled by a temperature control device. The detector detects a current flowing in the heater and/or a voltage applied to the heater. The controller controls an electrical power provided to the heater so as to be kept constant according to the detection result of the detector.

Optical device and method of controlling the same

An optical semiconductor device includes an optical semiconductor element, a metal pattern and at least one thermal conductive material. The optical semiconductor element has a first optical waveguide region and a second optical waveguide region. The second optical waveguide region is optically coupled to the first optical waveguide region and has a heater for changing a refractive index of the second optical waveguide region. The metal pattern is provided on an area to be thermally coupled to a temperature control device. The thermal conductive material couples the metal pattern with an upper face of the first optical waveguide region of the optical semiconductor element. The thermal conductive material is electrically separated from the first optical waveguide region.

Optical semiconductor element and optical semiconductor device

An optical semiconductor device has a heater, an optical waveguide layer, a first electrode and a second electrode. The heater is provided on a first semiconductor region and has more than one heater segment coupled or separated to each other. The optical waveguide layer is provided in the first semiconductor region and receives heat from the heater. The first electrode is coupled to a connecting point of the heater segments adjacent to each other. The second electrodes are electrically common and are coupled to other ends of the heater segments in opposite side of the connecting point respectively.

Optical semiconductor device

An optical semiconductor device includes a wavelength-tunable semiconductor laser chip, a mount carrier, a first temperature sensor and a wire. The wavelength-tunable semiconductor laser chip has a first optical waveguide and a second optical waveguide. The second optical waveguide has a heater on a surface thereof and is optically coupled to the first optical waveguide. The mount carrier is for mounting the wavelength-tunable semiconductor laser chip, and has a first area arranged at a surface of the mount carrier of the first optical waveguide side when the wavelength-tunable semiconductor laser chip is mounted. The first temperature sensor is mounted on the first area. The wire couples between the heater and a second area arranged at a surface of the mount carrier of the second optical waveguide side when the wavelength-tunable semiconductor laser chip is mounted.

Optical semiconductor device and controlling method of the same

A gain-coupled DFB laser diode includes a multiple quantum well active layer and a pair of cladding layers sandwiching the multiple quantum well active layer vertically, wherein the multiple quantum well active layer includes a plurality of gain regions aligned in a direction of propagation of a laser beam and repeated periodically, each of the gain regions having a multiple quantum well structure, and a buried layer fills a gap between a pair of adjacent gain regions, wherein the buried layer includes a plurality of high-refractive index layers and a plurality of low-refractive index layers, each of the high-refractive index layers is formed of a first semiconductor material having a first bandgap, while each of the low-refractive index layers is formed of a second semiconductor material having a second, larger bandgap.

Gain-coupled DFB laser diode

A method of manufacturing a distributed feedback semiconductor laser, has the steps of: growing on a semiconductor substrate a lamination of alternately stacked lower barrier layer and lower well layer having a band gap narrower than the lower barrier layer, to form a lower quantum well structure; growing an intermediate layer on an uppermost lower well layer, the intermediate layer having a band gap broader than the lower well and a thickness thicker than the lower barrier layer; growing on the intermediate layer a lamination of alternately stacked upper well layer and upper barrier layer having a band gap broader than the upper well layer and a thickness thinner than the intermediate layer, to form an upper quantum well structure; forming a mask on the upper quantum well structure, the mask having periodical pattern; by using the mask as an etching mask, etching the upper quantum well structure in a periodical shape by using the intermediate layer as an etching margin layer; and removing the mask. Complex coupling DFB lasers with a small variation in characteristics can be provided.

Complex coupling MQW semiconductor laser

A DFB laser in which a thickness of an active layer changes periodically and a greater part of current injected from external sides is selectively injected into the thick regions (projected regions) of the active layer. Therefore, the ratio of the gain coupling to the refractive index coupling can be further increased, and a threshold current can be lowered, and stability of single mode oscillation can also be improved.

Distributed feedback semiconductor laser

In a semiconductor light-emitting device including an MQW diffraction grating structure mainly used in a gain-coupled DFB laser, the ratio of the gain coupling coefficient to the index coupling coefficient is increased by making each well layer in MQW-A thicker than that in MQW-B. Each well layer and each barrier layer in the MQW structure are made of different compositions of GaInAsP. This implements a semiconductor light-emitting device with high wavelength stability, which does not induce any mode hop even during modulation with high output power or even when external optical feedback is present.

Growing community of inventors

Yamanashi, Japan

Tsutomu Ishikawa