Hitachi, Ltd.

Naoki Chinone

Kazuhisa Uomi

Takashi Kajimura

Tsukuru Ohtoshi

Shinji Sakano

Tadashi Fukuzawa

Yuichi Ono

Shinji Tsuji

Yasutoshi Kashiwada

Makoto Okai

Kunio Aiki

Hiroyoshi Matsumura

Tomonobu Tsuchiya

Michiharu Nakamura

Toshihiro Kawano

Hitoshi Nakamura

Satoshi Nakamura

Shinji Sasaki

Takao Kuroda

Shinichi Nakatsuka

Motohisa Hirao

Shin'ichi Nakatsuka

Ryoichi Ito

Akihiko Oka

Yoshihisa Fujisaki

Toshio Katsuyama

Hiroaki Inoue

Shigeo Yamashita

Hisao Nakashima

Misuzu Yoshizawa

Hideaki Matsueda

Toshiaki Tanaka

Akira Arimoto

Toshihisa Tsukada

Masahiro Aoki

Masahiro Ojima

Katsuyuki Imoto

Koji Ishida

Yasuhiro Shiraki

Kenji Hiruma

Toshiki P Tanaka

Jun-ichi Umeda

Yoshifumi Katayama

Yoshimasa Murayama

Kazuhiro Kurata

Akira Tonomura

Noriyuki Shige

Katsutoshi Saito

Hirobumi Ouchi

Yasutsugu Takeda

Yutaka Takeda

Nobutaka Ohnuki

Yuuichi Ono

Atsutoshi Doi

Hiroyoshi Matumura

Kazutoshi Saito

Yoshimitsu Sasaki

Katutoshi Saito

Hisao Nakajima

Akemi Yamanaka

Akio Oishi

Shinichi Nakatuka

Aiko Ohishi

A semiconductor laser device may include a structure formed separately of a light radiating region, and an electrode for injecting carriers over the light radiating region. A gap is formed between the light radiating region and the structure to introduce an air-bridge structure into the aforementioned electrode so that the capacitive component resulting from a presence of the electrode is drastically reduced.

Semiconductor laser device, method of fabricating the same and optical

A wavelength-tunable semiconductor laser device presenting a large wavelength-tunable range or a very-high-speed modulating semiconductor laser device having a distributed feedback structure including a diffraction grating as in the case of a DBR laser or a DFB laser incorporates therein a plurality of active layers differing from one another in constituent elements or composition ratio or thickness for reducing spectral line widths, while improving single-mode spectral oscillation characteristics.

Semiconductor laser device with plural active layers and changing

A wavelength tunable laser diode comprising a temperature variable heater separated from an active layer by a distance less than the thickness of a compound semiconductor substrate. Because the heater is located very close to the active layer, the response time of temperature change is improved. That in turn widens the tunable range of the laser diode.

Wavelength tunable laser diode

Disclosed in a semiconductor laser device for use in a system or apparatus utilizing light for information transmission in optical communication or the like, in which lattice defects or the like are prevented from occurring in the vicinity of a light-emitting active area to thereby reduce a leakage current which substantially makes no contribution to light emission. In order to realize the above semiconductor laser device, a wide gap area for preventing a leakage current is formed to be flat or formed to be spatially apart from the active area.

Semiconductor laser device suitable for optical communications systems

A semiconductor laser having a stripe-like lasing region, wherein the structure of the lasing region such as the mechanism of optical guiding of the lateral mode control structure is made different between the central portion in the lasing region and portions close to facets, in order to reduce optical feedback induced noise and astigmatism, and to facilitate the manufacture thereof.

Semiconductor laser

A semiconductor optical device having a region in which semiconductor or carriers in the semiconductor and light are interact, for example, an active region for a semiconductor laser, an optical wave guide region of an optical modulator, etc., includes a quantum well structure having a well region and a barrier region. The semiconductor optical device is remarkably improved with the degree of design freedom as it relates to parameters such as thickness and selection of material without deteriorating the quantum effect, by introducing a super lattice super-layer structure into the barrier region of the quantum well structure or defining the strain for the well region and the barrier region.

Semiconductor optical device

Semiconductor laser device capable of controlling wavelength shift

A semiconductor laser device of the field modulation type includes a structure in which the threshold carrier density for laser oscillation is reduced so as to enable an effective action of a modulated electric field applied externally on an active region for radiating light, thereby enabling an extremely high speed modulation. A quantum structure which does not fulfill the charge neutrality condition for free-carriers or a strained super lattice structure is adopted as the structure in which the threshold carrier density is reduced.

Semiconductor laser device

A semiconductor optical device in which an optical waveguide (3, 11) provided on a semiconductor substrate (1) comprises a strained-layer superlattice shows an extremely small transmission loss. A semiconductor optical device with further improved characteristics is obtainable by using a stained-layer superlattice for a portion required to show a great change in refractive index, such as an optical crosspoint switch portion (10), as well as for the optical waveguide (3, 11). The strained-layer superlattice comprises a first semiconductor layer and a second semiconductor layer having a narrower band gap and a greater lattice constant as compared with the first semiconductor layer, the two layers grown periodically.

A light emitting device has a multiple layer film structure such as a multiple quantum well (MQW) structure which is made of an indium system compound semiconductor not containing phosphorus, wherein part of a region or regions of the multiple film structure is (are) a disordered region or regions disordered by introduction of an inpurity.

Light emitting device with disordered region

A surface emitting laser diode having a two-dimensionally extended light emitting region is disclosed in which the light emitting region includes a plurality of stripe regions and gap regions each formed between adjacent stripe regions, the stripe regions are optically coupled with each other through the gap regions, and an even-order diffraction grating is formed in at least a part of the light emitting area. The laser diode having the above structure can emit a high-intensity, well-collimated laser beam.

Surface emitting type semiconductor laser

A tunable semiconductor laser device has an active region for generating light, and a feedback region which is optically coupled with the active region and includes a perturbation portion having non-uniform perturbation period. In this semiconductor laser device, the light intensity distribution in the feedback region is changed to vary the degree of coupling of light propagated in the feedback region with a desired part of the perturbation portion, thereby varying the wavelength of emitted light.

Semiconductor laser device of variable wavelength type

In a well-known semiconductor laser, a multiple quantum well type active layer consisting of barrier layers and active layers or well layers, each of which has a thickness less than the de Broglie wavelength of electrons, is doped with an impurity, and the impurity density is made higher in the barrier layer than in the well layer. Further, in a case where the multiple quantum well active layer is held between p-type and n-type cladding layers, the well layer is undoped, the part of the barrier layer lying in contact with the well layer is undoped, and the other part of the barrier layer close to the p-type cladding layer is put into the n-conductivity type while that of the barrier layer close to the n-type cladding layer is put into the n-conductivity type. Desirably, the impurity density should range from about 1.times.10.sup.18 to about 1.times.10.sup.19 cm.sup.- 3.

Semiconductor laser having a multiple quantum well structure doped with

In a well-known semiconductor laser, a multiple quantum well type active layer consisting of barrier layers and active layers or well layers, each of which has a thickness less than the de Broglie wavelength of electrons, is doped with an impurity, and the impurity density is made higher in the barrier layer than in the well layer. Further, in a case where the multiple quantum well active layer is held between p-type and n-type cladding layers, the well layer is undoped, the part of the barrier layer lying in contact with the well layer is undoped, and the other part of the barrier layer close to the p-type cladding layer is put into the n-conductivity type while that of the barrier layer close to the n-type cladding layer is put into the p-conductivity type.

Semiconductor laser having quantum well active region doped with

A wavelength-tunable semiconductor laser having an active part and an external waveguide part is disclosed. The external waveguide part has a diffraction grating, such as a distributed Bragg reflector, and a quantum well structure optically coupled to the diffraction grating, together with electrodes for impressing an electric field to the quantum well structure. By applying the electric filed to the quantum well structure, the refractive index in the optically coupled diffraction grating/quantum well structure, and light oscillation wavelength in the external waveguide part, can be varied.

Wavelength-tunable semiconductor laser

Growing community of inventors

Hachioji, Japan

Naoki Chinone