Abstract: An optical modulating device including a driving circuit generating a driving voltage corresponding to an input signal, an oscillator generating a signal having a low frequency signal lower than that of the input signal, an MZ modulator receiving a DC bias voltage superposed with the low frequency signal and the driving voltage, to generate a modulated optical signal according to the input signal, a photoelectric converting unit for converting the modulated optical signal into an electric signal, a low frequency signal detecting circuit which extracts the low frequency signal component contained in the electric signal, multiplies the low frequency signal component by the low frequency signal outputted by the low frequency oscillator, and then extracts a DC component from a multiplied output signal, and a control circuit for extracting a maximized DC component from the low frequency signal detecting circuit by controlling the DC bias voltage.

Abstract: A substrate has a principal surface exposing a first semiconductor material. A micro structure is disposed on the principal surface of the substrate. The micro structure is made of a second semiconductor material having a lattice constant different from a lattice constant of the first semiconductor material, and defines a three-dimensionally irregular upper surface. A strained layer is disposed on the micro structure. The strained layer is made of a third semiconductor material having a lattice constant different from a lattice constant of the first semiconductor material. A semiconductor device is provided which has the structure allowing to form a high quality strained layer in terms of crystallography.

Abstract: Carriers are injected into a plurality of quantum dots by applying a bias voltage to a semiconductor region of a semiconductor optical amplifier, the plurality of quantum dots for three-dimensionally confining carriers being distributed in the semiconductor region. An optical pulse signal at a bit rate of 2 Gb/s or higher is input to the semiconductor optical amplifier which amplifies the input optical pulse signal by generating induced emission by optical transition of the carriers in the quantum dots. An optical signal processing method capable of high speed and stable operation is provided.

Abstract: A pulse current component of a driving current is determined, based on a current-optical output coefficient derived using average optical output information of a semiconductor light-emitting element. A bias current component can be set by adjusting an average optical output of the semiconductor light-emitting element while changing the bias current component by the driving current including the determined pulse current component. Since the current-optical output coefficient can be derived based on the average optical output under wide conditions, both the pulse current component and the bias current component can be determined under the wide conditions and without using a quick-response light detector.

Abstract: There are provided a first optical transmitting device for transmitting a first light having a first wavelength in a continuous light state and a second light having signal optical pulses and a second wavelength, a first optical amplifier for receiving the first light and the second light from the first optical transmitting device, a pulse light source for outputting a controlling optical pulse train having a third wavelength, a second optical transmitting device for transmitting the first light, on which a waveform is superposed by the first optical amplifier, and the controlling optical pulse train being output from the pulse light source, and a second optical amplifier for receiving the first light and the controlling optical pulse train from the second optical transmitting device and then outputting an output optical signal having the third wavelength, on which the signal pulse is superposed.

Abstract: Carriers are injected into a plurality of quantum dots by applying a bias voltage to a semiconductor region of a semiconductor optical amplifier, the plurality of quantum dots for three-dimensionally confining carriers being distributed in the semiconductor region. An optical pulse signal at a bit rate of 2 Gb/s or higher is input to the semiconductor optical amplifier which amplifies the input optical pulse signal by generating induced emission by optical transition of the carriers in the quantum dots. An optical signal processing method capable of high speed and stable operation is provided.

Abstract: Optical signals inputted to input ports are split in half by 1×2 optical splitters respectively and the resulting signals are inputted to the input terminals of an optical matrix switch. The optical matrix switch switches between the routes of the individual optical signals and outputs the signal at any of the output ports. This enables the optical signal from the same input port to be outputted at two different output ports, which makes it possible to effect “bridge” at the time of protection switching.

Abstract: A substrate has a principal surface exposing a first semiconductor material. A micro structure is disposed on the principal surface of the substrate. The micro structure is made of a second semiconductor material having a lattice constant different from a lattice constant of the first semiconductor material, and defines a three-dimensionally irregular upper surface. A strained layer is disposed on the micro structure. The strained layer is made of a third semiconductor material having a lattice constant different from a lattice constant of the first semiconductor material. A semiconductor device is provided which has the structure allowing to form a high quality strained layer in terms of crystallography.

Abstract: A user apparatus periodically detects the mount state of any terminal interface card, and transmits, to a center apparatus, configuration information indicative of the configuration of the user apparatus and including the detection result, when responding to a request for delay time measurement. The center apparatus recognizes and manages the configuration of the user apparatus on the basis of the configuration information. When newly mounting or removing of a terminal interface card has been recognized, the center apparatus performs newly setting releasing of a destination identifier corresponding to the mounted or removed terminal interface card, and notifies the user apparatus of the newly set destination identifier. The user apparatus, in turn, manages identification information sent from the center apparatus, in relation to the terminal interface unit corresponding to the information. As a result, exchange, addition or cancel of communication services which the user uses can be performed easily.

Abstract: In a process for preparing a fluorinated olefin having a carbon—carbon double bond, the carbon atoms of which have a fluorine atom, by reacting a halogenated olefin having at least one carbon—carbon double bond, a carbon atom or the carbon atoms of which bond have a chlorine atom or atoms bound thereto, and, in which the carbon atom or atoms with a single bond in the molecule have no halogen atom other than a fluorine atom, with an alkali metal fluoride, said reaction of the halogenated olefin with the alkali metal fluoride is conducted in the presence of an organic halogen-containing compound having a carbon—carbon single bond, a carbon or the carbons of which have at least one halogen atom other than fluorine atom.

Abstract: An optical pulse train generated by an optical pulse generator and an oscillator is coupled into a polarization switcher to polarize two successive pulses perpendicular to each other. The optical pulse train is amplified by an EDFA, then entered into an SC fiber so that the optical spectrum is broadened. The optical pulse train output from the SC fiber is then directed to an optical wavelength demultiplexer for demultiplexing into components of desired wavelengths. In this case, since successive pulses are polarized perpendicular to each other, there is no need to use polarization maintaining fiber for the SC fiber and for connection optical modulator. In particular, if the polarization made dispersion of the SC fiber is sufficiently small, the SC pulses polarized perpendicular to each other will not overlap or be superimposed upon each other in time domain. Thus, the time-averaging degree of polarization can be held zero and non-polarized wideband white pulses can be obtained.

Abstract: In an optical receiver circuit in which an optical input signal is amplified by an optical amplifier and converted to an electrical signal by optical detector, and the amplified optical signal is amplified by an equalization amplifier so as to obtain an optical received signal, an output peak level of the equalization amplifier is detected by a peak detection circuit, an error difference of the peak level is amplified by an error amplification circuit, and a gain of the optical fiber amplifier is controlled by a gain control circuit, thereby fixing a level of the received signal. In the above-mentioned structure, an input signal loss detection circuit detects an input signal loss from an output of the peak detection circuit, and the gain of the optical fiber amplifier is controlled by the gain control circuit to be sufficiently lower than the maximum gain at the time of the detection.

Abstract: An InP p-n diode having an MQW consisting of an InP barrier layer and an In.sub.1-x Ga.sub.x As well layer as an active layer. An optical modulating diode in which a composition of a value 0.44 which is smaller than the x value 0.47 at which lattices are matched is selected so as to cause compressive strain in the well layer, and an optical bistable diode in which a composition of a value 0.55 which is greater than 0.47 is selected so as to cause tensile strain in the well layer.

Abstract: An optical intensity modulator includes a compound semiconductor substrate of a first conductivity type having first and second surfaces, and a compound semiconductor active layer of the first conductivity type formed on the first surface of the compound semiconductor substrate. An incident laser beam to be intensity-modulated is applied to the compound semiconductor active layer. The modulator further includes a compound semiconductor layer of the first conductivity type formed on the compound semiconductor active layer, an opposite conductivity type compound semiconductor layer of a second conductivity type opposite to the first conductivity type, a first electrode formed on the opposite conductivity type compound semiconductor layer, and a second electrode formed on the second surface of the compound semiconductor substrate.

Abstract: An optical communication apparatus which comprises a printed circuit board, plural circuit elements fixed to the printed circuit board, the circuit elements having terminals extended to the printed circuit board, a photosensitive glass base fixed to the printed circuit board, various optical components accurately fixed to the glass base, the optical elements respectively having plural leads, and corresponding conductive members for electrically connecting the terminals of the circuit elements and the corresponding leads of the optical components, the conductive members each having a rigidity smaller than the rigidity of the corresponding leads of the optical components.

Abstract: A semiconductor substrate comprising: a single-crystalline semiconductor wafer substrate; a strained layer superlattice (SLS) structure layer formed on the wafer substrate; and a compound semiconductor epitaxial layer formed on the SLS structure layer. According to the present invention, the SLS structure layer consists of pairs of a first compound semiconductor thin layer and a second compound semiconductor thin layer, the first and second thin layers having the same components in a compound system having a miscibility gap, and having different compositions outside of the miscibility gap including the limit line of the miscibility gap, respectively, at a temperature higher than that of heat-treatments applied to the compound semiconductor substrate, without a decay of the SLS structure.

Abstract: A device for receiving optical signals in which optical signals from an optical fiber are focused by a lens. A holder holds the fiber and the lens and is fixed to a case. The light receiving element is included in the case and can receive the optical signals from the lens through a hole in the case. A seal covers the hole and is able to pass the optical signals from the lens to the light receiving element.

Abstract: An optical circuit device includes an optical fiber element, a lens and several holders. An inner holder which is elastic, holds the optical fiber element and a lens on the same optical axis. An intermediate holder fixes the inner holder therein. An outer holder, which is connected to an optical signal receiving device, holds the intermediate holder therein. An optical axis of the inner holder is adjusted by shifting the position of the intermediate holder in the outer holder parallel to the optical axis. Also, the optical axis is adjusted by moving the outer holder perpendicular to the optical axis.