Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: An optical device utilizes a polariton substance and utilizes the absorption wavelength band of excitonic polaritons. Further, an external stimulus such as electric field, magnetic field, stress, current or electromagnetic wave (light) is continuously or intermittently given to the polariton substance, thereby to modulate light which enters the optical device. Thus, a modulating operation of ultra-high speed is possible.

Abstract: This invention discloses a semiconductor laser capable of a high temperature and high output operation by forming a mesa stripe having an active layer in a reverse triangular mesa shape and forming thick semiconductor layers on both sides of the mesa stripe in such a manner that the resulting p-n junctions have a current blocking function. The invention discloses also a semiconductor laser wherein the formation of the p-n junctions described above is made before the formation of the reverse mesa stripe, and ion implantation is introduced in order to form the p-n junctions. Furthermore, the invention relates to transistors and semiconductor lasers using InGaAsP type quaternary compounds as the semiconductor. The quaternary compounds having a composition in which an energy band gap is from 1.2 to 1.4 eV are formed in a thickness of up to 1 .mu.m, and there can be thus obtained semiconductor devices having a small leakage current and being stable with time.

Abstract: A semiconductor device comprises a first superlattice layer consisting of a first semiconductor layer that contains impurities and a second semiconductor layer that contains impurities at a low concentration, said first superlattice layer being formed on a semiconductor substrate; and a second superlattice layer that covers that exposed side walls of said first superlattice layer. A disordered region is formed in the vicinity of the first semiconductor layer of the second superlattice layer in order to realize quantum wires with the conventional manufacturing process. This makes it possible to easily fabricate a laser device, a light-emitting diode and a transistor having quantum wires to enhance their performance.

Abstract: A semiconductor laser device including at least one of a laser active layer formed of a super lattice and an optical guide layer formed of another super lattice is disclosed in which part of at least one of the super lattices is converted into a mixed crystal by the impurity induced disordering based upon one of impurity diffusion and impurity ion implantation, to divide the super lattice into a first region formed of the mixed crystal and a second region having the super lattice structure, the width of the second region in directions perpendicular to the lengthwise direction of a laser cavity varies along the above lengthwise direction, and the width of a laser excitation region is smaller than the mean value of the width of the second region, to generate laser oscillation having a single transverse mode and a multi longitudinal mode. Thus, the semiconductor laser device emits a laser beam which is small in astigmatism and low in optical feedback noise.

Abstract: A stripe groove is formed on a semiconductor substrate and buried by lamination of multiple semiconductor layers, and a channel being lower than the substrate surface is formed outside the groove near at least one mirror edge, such that a laser diode with decreased astigmatism can be produced.