Abstract: The present invention relates to an electric appliance and a remaining life estimation system wherein the electric appliance having a printed circuit board on which at least LSI components are mounted includes an IC with sensor. The IC includes a time monitor for calculating the operation status which is a use condition affecting the life of a reusable component of the appliance, a temperature and humidity sensor for detecting at least temperature and humidity environmental conditions affecting the life of the reusable component, and a memory for storing the history of temperature and humidity in correspondence with the history of operation status.

Abstract: A method of fabricating diffraction gratings wherein a photomask is arranged on a substrate which is coated with a photoresist, light is to be incident thereupon at an acute angle relative to the normal direction of the photomask, and a bright/dark pattern is formed on said photoresist by the interference of the transmission light that has passed through the photomask and the diffraction light. The invention further deals with a photomask used for the above method.

Abstract: A semiconductor optical device in which a hetero-structure is constructed by sandwiching a semiconductor layer including a thin film made of a semiconductor or insulator between semiconductors having a larger band gap than that of the thin film so that the electron-hole pairs generated through the thin film may recombine by the tunnel effect to emit an optical beam. The optical device is equipped with electrodes for controlling the probability of said recombination.

Abstract: A semiconductor device such as a semiconductor laser device or a transistor which is small in both threshold current and leakage current and exhibits no increase with time in the threshold current and leakage current can be obtained by incorporating pnp or npn junctions in a buried layer which coats an active region containing InGaAsP, forming the mid layer of the junctions with InGaAsP, adjusting the conductivity type of the mid layer with an implanted ion and specifying the energy band width of a semiconductor constituting the mid layer.

Abstract: An optical device having a material exhibits an optical rectification effect is disclosed. The optical device utilizes direct current polarization which is induced in the material by a control light. The induction of the direct current polarization in the material by the control light changes the refractive index and absorption spectrum of the material. This is based on the so-called electrooptic effect and Franz-Keldysh effect. The present invention provides the optical device according to which external incident light can be modulated at high speed with the control light by utilizing the change of the refractive index or the change of the absorption spectrum.

Abstract: An optical device and an optical integrated circuit which incorporate an optical switch and have a novel function. Light sources are respectively coupled to two input ends of an X-type 2.times.2 optical switch, and light receivers are respectively coupled to two output ends of the optical switch, thereby obtaining an optical device which is capable of performing both AND and OR logics. A light source is coupled to one input end of an optical switch, and a light receiver is provided at one output end from which the light emitted from the light source emerges when no electric power is supplied to the optical switch, whereby it is possible to construct a system in which, even when one terminal has a power failure, there is no hindrance to other terminals. If an optical switch is arranged such as to use driving electric power as a modulating signal, the optical switch can serve as a modulator in which the output from one output end can be employed to monitor a modulated optical signal.

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: An optical modulator which utilizes the Stark effect according to which the absorption spectra change if an electric field is applied to the excitons. A thin film of a suitable thickness composed of a semiconductor and an insulator or composed of either one of them, is formed between a group of electrons and a group of positive holes that constitute excitons, so that the excitons are stabilized. The optical modulator performs the modulation at high speeds maintaining a high efficiency.

Abstract: A multi-quantum well structure which is formed by laminating thin semiconductor layers is provided with means for injecting carriers in a direction which is parallel to the surface of the laminated thin semiconductor layers, whereby it is possible to obtain satisfactory changes in refractive index of the carrier injection portion. For example, if the total reflection region of an optical switch consisting of optical waveguides which cross each other is provided with a multi-quantum well structure wherein carriers are injected in a direction parallel to the surface of the well, the extinction ratio characteristics of the device can be improved.

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: In a semiconductor device wherein a signal transmission in a semiconductor integrated electronic circuit is carried out partly or entirely by means of a light, the signal transmission on the light is carried out with multi-wavelength, waveguides or a photoelectric converter and an electronic integrated device are provided on a circuit board having an optical waveguide, thus providing a high performance and practical technique.

Abstract: Disclosed is a semiconductor device comprising a first semiconductor layer, a second semiconductor layer, and a third semiconductor layer which is formed between the first semiconductor layer and the second semiconductor layer and a band gap of which is narrower than that of each of the first and second layers, so that band discontinuities in conduction bands and valence bands of the three layers form a barrier to the third semiconductor layer, and that a tunneling current can flow through the third semmiconductor layer owing to an internal electric field of the third semiconductor layer.

Abstract: Electrodes are provided in the vicinity of the switching region of a carrier injection type optical switch, and carriers are removed rapidly through these electrodes when the switch is turned OFF. As the result, a switching speed is increased.

Abstract: An optical fiber having an intense polarization plane maintenability is constructed of an optical waveguide having a circular core and a circular cladding, a jacket formed on the outer circumference of the optical waveguide and having an elliptical outer circumference, and a supporting portion formed on the jacket.In order to fabricate the above-specified optical fiber, a preformed rod therefor is prepared by forming the inner wall of an silica glass tube with the jacket and the optical waveguide made of such materials as satisfy a relationship of c.sub.2 /a.gtoreq.200/(100-.gamma.)-1, wherein: letter .gamma. stands for the ellipticity of the outer circumference of the aforementioned jacket; letter c.sub.2 stands for the minor axis of an ellipse; and letter a stands for the radius of the circular optical waveguide, and by subsequently collapsing the aforementioned silica glass tube while having its internal pressure made lower than the atmospheric pressure by 1 to 20 mmH.sub.2 O.

Abstract: A novel method which enables a quaternary III-V group crystal to be readily formed on a III-V group crystal so that the former crystal lattice-matches with the latter crystal. More specifically, it is easy to produce a superlattice structure on a III-V group crystal substrate, the superlattice structure consisting of a first III-V group (hereinafter referred to as "III.sup.1 -V.sup.1 ") binary crystal layer which lattice-matches with the substrate, and a III-V group (III.sup.1 -III.sup.2 -V.sup.2) ternary crystal layer which similarly lattice-matches with the substrate. It is possible to obtain an even more stable superlattice layer by selecting the ratio between the film thickness of the (III.sup.1 -V.sup.1) crystal and the film thickness of the (III.sup.1 -III.sup.2 -V.sup.2) crystal so that, when the superlattice structure is mixed-crystallized spontaneously or by means of impurity doping, the mixed-crystallized composition lattice-matches with the previous crystal.

Abstract: Herein disclosed is a branch type optical switch having three or more optical waveguides capable of being coupled to one another in a coupling region, in which is formed a refractive index changing portion for effecting the function of the branch type optical switch by changing the refractive index thereof. This optical switch has a small coupling loss and an excellent extinction ratio. Also disclosed is an intersection type optical switch having two or more optical waveguides intersecting each other. The input optical waveguide and the output waveguide are connected at their intersection by means of a bypass optical waveguide to construct the above-specified branch type optical switch in the coupling regions of the bypass optical waveguides and the input and output optical waveguides, and the bypass optical waveguide has a curved or polygonal shape. Thus, it is possible to provide a small-sized optical switch which has an excellent extinction ratio and little variability in characteristics.

Abstract: A semiconductor device in which two sorts of compound semiconductors having unequal lattice constants are joined, is disclosed.Defects such as dislocations attributed to lattice mismatching are avoided by subjecting one of the compound semiconductors to atomic layer doping with an impurity. Owing to this construction, it is permitted to combine the optimum materials as the compound semiconductors, and the semiconductor device has its performance improved and its design versatility expanded.

Abstract: It is possible to narrow the emission spectrum linewidth of a semiconductor laser device by coupling optically an external resonator with one end surface of the semiconductor laser. However, the structure of the external resonator should match the phase of the light emitted by the laser. Heretofore, this matching has been effected by adjusting the length of the external resonator, and hence productivity and reproducibility have not been good. According to this invention, characteristics of the external resonator can be adjusted electrically to be matched with the phase of the emitted light owing to the fact that the external resonator is made of a material, whose refractive index can be varied electrically. Therefore the semiconductor laser device according to this invention is very practical.

Abstract: A method and equipment for fabricating two diffraction gratings having the same period but phases that are shifted by .lambda./4 on a work to be treated. A laser beam is divided into two light beams and one of the beams is delayed over a portion of the light beam. The divided light beams are then mixed together so that they interfere. Using the known photolithography technology, the interference patterns are formed into diffraction gratings.

Abstract: When a semiconductor device is produced by growing epitaxially a compound semiconductor layer on a Si or Ge substrate, lattice matching between the substrate crystal and the compound semiconductor layer to be formed on the substrate can be improved by ion-implanting an ion species element, which increases the lattice constant of Si or Ge as the substrate, into the Si or Ge substrate in order to increase its lattice constant. In comparison with conventional semiconductor devices using Si or Ge into which ion implantation is not made, the semiconductor device produced by the method described above can improve remarkably its characteristics. In the case of a semiconductor laser device, for example, its threshold value drops drastically and its service life can be prolonged remarkably.