Abstract: A power supply system includes a movable power supply device including a first power storage device, a robot including a second power storage device, and a controller, and the controller performs control for conveying the first power storage device to the robot by using the power supply device, on the basis of information about an amount of power stored in the second power storage device.

Abstract: An object of this invention is to improve wavelength selectivity. Two optical waveguides (10 and 12) are disposed side by side on surfaces at different heights from each other, and a diffraction grating (14) is disposed between them. The two optical waveguides (10 and 12) cross at an angel &thgr; in an area (16) where they mutually approach. Here, &thgr; is not zero, and preferably should be approximately 0.5°.

Abstract: A diffraction grating is disposed adjacent to a ridge waveguide formed on a substrate (cladding). Assumed that a light propagation direction at the waveguide is z, a direction of width of the waveguide is x, and ends of the diffraction grating of this embodiment is x=gmin when z=0 and x=gmax when z=L/2, the ends of the diffraction grating can be expressed as the following functions f(z). Namely, f(Z)=gmin+(gmax−gmin)×(2z/L)n when 0≦z≦L/2, and f(Z)=gmin+(gmax−gmin)×(2-2z/L)n when L/2≦z≦L, where n>1.

Abstract: The present invention provides a semiconductor memory capable of retaining information after removing a power supply and of storing information with an optical input. A memory cell is comprising an n-InP substrate, a first semiconductor (n-InGaAs) layer, a second semiconductor (i-InGaAs) layer, a third semiconductor (p-InGaAs) layer, a fourth semiconductor (i-InGaAs) layer and a fifth semiconductor (n-InGaAs) layer. The first to fifth semiconductor layers are stacked in this order on the n-InP substrate. A bias voltage is applied between the n-InP substrate and the fifth semiconductor layer to control a height of a TBD formed in the above multi-layer structure so that carriers may move and electrons can be stored in one of the second and fourth semiconductor layers.

Abstract: An optical processor comprising, a semiconductor saturable absorber; a current source for injecting a current to the semiconductor saturable absorber; a signal light introducer for introducing a signal light to the saturable absorber; a control light introducer for introducing a control light having a wavelength not longer than the wavelength of the signal light into the semiconductor saturable absorber; an assist light introducer for introducing an assist light having a wavelength longer than the wavelength of the signal light into the semiconductor saturable absorber; and a signal light extractor for extracting the signal light after treatment by the semiconductor saturable absorber.

Abstract: The coupled waveguide structure comprises first and second rectangular waveguides, disposed closely. The aspect ratio of the first waveguide is substantially inverse in number to that of the second waveguide.

Abstract: A functional semiconductor element, which is designed to perform an ultrafast amplifying, bistable, similar functional operation by initiating and stopping an avalanche multiplication in one of i-type layers of what is called a triangular barrier diode (TBD) structure having an n-i-p-i-n, p-i-n-i-p, n-i-p-i-p, n-i-n-i-p, n-i-n-i-n, p-i-n-i-n, p-i-p-i-p, or p-i-p-i-n configuration. By forming a light absorbing layer and a light emitting layer or light modulating layer in this structure, it is possible to function the element as an optical functional element. Furthermore, the addition of a resonant tunneling diode implements a novel function.

Abstract: An optical short pulse reshaping device capable of effectively eliminating noise from or reshaping of input optical short pulses of a pulse width of picosecond order shorter than a carrier life time. The device comprises: a semiconductor laser element, means for injecting an electric current to the semiconductor laser element for obtaining an oscillation state of the semiconductor laser element, means for injecting into the semiconductor laser element input optical short pulses of a wavelength shorter than that of the oscillation light of said semiconductor laser element, and means for taking out optical short pulses emitted from the semiconductor laser element in distinction from its oscillation output light.

Abstract: An optical add/drop multiplexer device which is capable of extracting or inserting optical signals of arbitrary wavelength and having a wavelength selection characteristic with a narrow bandwidth, and which is compact in size and highly reliable. The device is formed by a substrate member; a plurality of optical waveguides, formed over the substrate member in layers with a prescribed interval along a direction perpendicular to a plane of the substrate member, each optical waveguide having a portion arranged in parallel and in proximity to an adjacent optical waveguide to form a coupling section; and a diffraction grating member, provided at the coupling section and having a prescribed period along a light propagation direction, for reflecting light signals with a specific wavelength among light signals entered from one of adjacent optical waveguides to another one of the adjacent optical waveguides.

Abstract: There is disclosed a reshaping device for optical short pulses to effectively perform reshaping of and eliminate noise from an optical short pulse of a pulse width of pico second order less than a carrier life time. Input optical short pulses are applied to a saturable absorption element, while an assist light of a wavelength longer than that of the input optical signal pulses is also applied to the saturable absorption element to accelerate, by stimulated emission, recombination of excited electrons and holes produced in the saturable absorption element in response to the input optical signal pulses, so that the input optical signal pulses reshaped are derived from the saturable absorption element.

Abstract: The short optical pulse generator is provided with a semiconductor laser which oscillates continuously at a single wavelength, a semiconductor electro-absorption type optical modulator which performs the intensity modulation of the output light from the laser, and a sinusoidal voltage generator and a DC voltage generator for driving the electro-absorption type optical modulator. A DC voltage is applied to the electro-absorption type optical modulator so that the output light from the laser is sufficiently extinguished. By applying a sinusoidal voltage to the optical modulator, short optical pulses are generated.

Abstract: An optical device includes a semiconductor optical modulator element (46) which is connected to an end of a signal line (42) in form of a microstrip high-frequency line and whose other electrode is connected to a ground electrode (48) by a bonding wire (50). The signal line (42) includes first and second line portions (42a, 42b). The first line portion (42a) nearer to the entrance of a high-frequency signal has a width W1 determined to adjust its characteristic impedance to 50.OMEGA. and a length L1 equal to an integer multiple of 1/4 of its own guide wavelength. The second line portion (42b) has a width W2 determined to adjust its impedance to an intermediate value between the impedance of the optical modulator element 46 and the impedance of the first line portion (42a), and a length L2 equal to an integer multiple of 1/4 of its own guide wavelength.

Abstract: An optical functional semiconductor element which performs ultrafast, high-contrast logic operation through utilization of the high speed of light velocity. A resonant-tunneling diode having a negative resistance characteristic is provided apart from a light absorbing layer formed by one of i-type layers of what is called a triangular barrier diode of an nipin or pinip structure, by which as the quantity of incident light increases, the quantity of transmitted current is switched from increase to decrease, the amount of change is made high-contrast and an ultrafast logic operation can be performed.

Abstract: An optical short pulse generating device is disclosed, in which semiconductor laser light of a fixed intensity is launched into a first semiconductor electroabsorption optical modulator which is driven by a 0V or forward bias voltage and a sinusoidal voltage, and the output light from the first optical modulator is launched into a second electroabsorption optical modulator to which is applied a bias voltage and a sinusoidal voltage having delayed from the said sinusoidal voltage for a period of time corresponding to the phase reversal thereof, whereby it is possible to generate optical short pulses of a repetition frequency twice higher than the oscillation frequency of a sinusoidal voltage generator.

Abstract: To perform waveform shaping, retiming and amplification of the transmitted pulse signal of a binary PCM fiber optic communication employing an optical pulse signal which has a pulse duty factor within 1 with respect to a time slot, an optical waveform shaping device is proposed in which the optical pulse signal is branched by an optical branch circuit into two optical signals. The one transmitted optical signal passes through a photodetector, a band-pass filter for extracting the fundamental frequency component of the signal, an amplifier and a delay circuit, so that the signal is converted to a sinusoidal voltage synchronized with the optical pulse signal. The other optical signal passes through a semiconductor electrical absorption type optical modulator which is driven by the sinusoidal voltage and a DC voltage, so that the width of a gate waveform is changed by controlling the amplitude of the sinusoidal voltage and the DC voltage.

Abstract: The short optical pulse generator is provided with a semiconductor laser which oscillates continuously at a single wavelength, a semiconductor electro-absorption type optical modulator which performs the intensity modulation of the output light from the laser, and a sinusoidal voltage generator and a DC voltage generator for driving the electro-absorption type optical modulator. A DC voltage is applied to the electro-absorption type optical modulator so that the output light from the laser is sufficiently extinguished. By applying a sinusoidal voltage to the optical modulator, short optical pulses are generated.

Abstract: A multiple quantum well structure which permits substantially uniform injection of carriers from the outside into respective quantum well layers of the multiple quantum well and a semiconductor device employing such a multiple quantum well structure. A multiple quantum well structure is formed by laminating at least two pairs of quantum well layers each having a thickness substantially equal to the de Broglie's wave-length of electrons and barrier layers of an energy gap greater than that of the quantum well layers, and the multiple quantum well structure is doped with at least one of p-type and n-type impurities in a manner to slope the energy band of the entire multiple quantum well structure so that carriers injected thereinto are distributed uniformly throughout it.

Abstract: An optical modulator in which waveguide regions are disposed at opposite ends of a modulation region to reduce the capacitance of the device and prevent pn junctions from exposure to air. On an n-side electrode there are laminated a substrate, an n-type clad layer and an optical modulation waveguide layer. A modulation region lies at the center of the optical modulation waveguide layer along the direction of travel of light, and two waveguide regions are disposed at opposite ends of the modulation region, respectively. On the optical modulation waveguide layer which constitutes the modulation region there are laminated a non-doped layer, a p-type clad layer and a p-side electrode, and a semi-insulating semiconductor is formed on the optical modulation waveguide layer which forms the two waveguide regions.

Abstract: An optical logic element is disclosed which performs an XOR operation through utilization of the high-speed property of light. On each branched waveguide of a Mach-Zehnder interference type optical waveguide there is provided a phase modulating element whose refractive index undergoes a change when it is irradiated by light. The interference type optical waveguide is adapted to provide different optical output levels when the refractive index changes of the phase modulating elements are both zero or a predetermined value and when they differ from each other. Thus, the optical logic element is capable of performing the XOR or XNOR operation at an ultrahigh speed.

Abstract: A semiconductor device with a strained-layer superlattice is disclosed, in which a first semiconductor and a second semiconductor of a lattice constant smaller than that of the first semiconductor are stacked on a clad layer of a lattice constant substantially intermediate between those of the first and second semiconductors to form the strained-layer superlattice. The lattice constant of the strained-layer superlattice in the direction of its plane in the free space is nearly equal to the lattice constant of the clad layer. A third semiconductor of a lattice constant substantially equal to that of the clad layer is laminated between the first and second semiconductors stacked one on the other.