Abstract: Disclosed are a datalink system, which has: a data transmission system which is composed of a parallel-to-serial converter which converts a parallel signal into a serial signal, a data transmission line which transmits the serial signal output from the parallel-to-serial converter and a serial-to-parallel converter which converts the serial signal transmitted through the data transmission line into the parallel signal; and a control signal transmission system which is composed of a control signal transmission line and lies in parallel with the data transmission system, and a communication network which has a data network and a control signal network.

Abstract: In an optical transmission system comprising an optical branch unit, first through fourth OR/OS pairs each of which includes optical receiver and optical transmitter, optical switch devices for active and standby systems, each of the optical switch devices having an N number of input ports and M number of output ports; and an optical multiplexer for multiplexing an M number of optical signal supplied from the third OR/OS pair and an M number of optical signals supplied from the fourth OR/OS pair to produce an M number of optical signals, the optical switch devices and the first through the fourth OR/OS pairs have a 3-dB margin with respect to the input optical strength. First and second paths are each adjusted such that the time required for transmitting an optical signal is identical for all paths.

Abstract: Disclosed is an optical network device for connecting a plurality of processors in a multiprocessor system, which has: a plurality of network interface devices corresponding to the plurality of processors; and an optical switch device; where each of the plurality of network interface devices comprises an optical transmitter and an optical receiver which are connected with the optical switch device through optical fibers and a network interface control circuit, the optical switch device comprises an optical switch connected with the optical transmitter and the optical receiver and an optical switch control circuit, the network interface control circuit and the optical switch control circuit are connected with each other through a transmission request signal line, a transmission-ending signal line and a transmission-start request signal line, the network interface control circuit sends out a transmission request with an addressee address through the transmission request signal line and notifies the optical swit

Abstract: Parallel digital data are transmitted along with a specific synchronization pattern added thereto. Each synchronization pattern adder adds the synchronization pattern at an equal timing for each channel. Parallel data after the synchronization pattern addition, are converted in parallel-to-serial converters into serial data which are in turn converted in an optical transmitter into optical signal. On the receiving side, the optical signal is converted in an optical receiver into an electric signal, from which the parallel data are restored in serial-to-parallel converters to be inputted to synchronization pattern detectors. The synchronization pattern detectors compare their shift register data and synchronization pattern and hold their synchronization pattern detection signal to be "1" for one time slot if the number of non-accord bits is within one. In the next time slot, a controller recognizes synchronization pattern detection when and only when all the synchronization pattern detection signals are "1".

Abstract: The present invention provides means by which a switch controller that manages lines directly notifies receivers of ineffectiveness of received data upon line disconnection instead of any transmitter indirectly notifying receivers; and according to the invention, an optical transmitter is provided within the optical switching unit, and a switch controller controls the optical transmitter within the optical switching unit and an optical switch having at its input ports one or more dummy ports capable of multicast-transmission. According to this control, upon line disconnection, receivers are connected to the optical transmitter within the optical switching unit that transmits control code in real time, thereby preventing receivers from receiving ineffective data and obviating superfluous signal lines and communication processes between the switch controller and transmitters.

Abstract: Disclosed is a high-speed frequency modulation signal source which has a voltage-controlled oscillator to which a voltage is input to change an oscillation frequency; and a frequency down converter in which a frequency output from the voltage-controlled oscillator is converted into a desired frequency. Also disclosed is a high-speed variable optical wavelength filter which has the above high-speed frequency modulation signal source; a band-pass filter in which a frequency component is extracted from the desired frequency output from the high-speed frequency modulation signal source; and an acousto-optic filter which is driven by the frequency component output from the band-pass filter.

Abstract: An optical communication network for quickly detecting faults and rerouting data using the optical signals in their light form, superimposes a monitoring signal on an optical data signal. The optical data signal and the monitoring signal are superimposed by, for example, wavelength-multiplexing or polarization-multiplexing. A receiving node receives the superimposed signal and splits it back into the optical data signal and the monitoring signal. A processor in the receiving node analyzes the monitoring signal to determine whether a fault exists in the transmission path. Similarly, the processor can analyze the data signal to determine whether a fault exists in a previous node or repeater. Once a fault is detected, the signal can be quickly rerouted (detoured) around the faulty section (node).

Abstract: An optical communication scheme is carried out by using a network having a plurality of nodes, a first network medium connected to a first group of the nodes, and a second network medium for transmitting control signals and connected to a second group of nodes. When initiating data transmission, any of the nodes transmits a transmission signal to the first network medium, and a receiving node that has received the signal loops-back the same signal to the second network medium thereby communicating information as to a state of congestion at the receiving node. A network for large volume data transmission can be realized by simple hardware and the state of congestion can be controlled using a simple method.

Abstract: A parallel signal of a k bit width is converted such that every m bits of width is made a byte. It is then coded by a plurality i of encoders into a t byte error correcting code in which a byte length is of m bits and a code length is of 1 bytes. The coded parallel signal is interleaved by an interleaver and is distributed into a plurality 1 of transmitters. Each transmitter converts the parallel signal of an mi bit width into a serial signal and transmits the converted signal. Each receiver converts the received serial signal into a parallel signal of an mi bit width and outputs the signal thus converted. The signals outputted from a plurality i of receivers are deinterleaved by a de-interleaver, and the deinterleaved signals are inputted to a plurality i of decoders. The decoders carry out correction of a t byte error in which one byte is of m bits, and integrates the signals outputted therefrom and outputs a parallel signal of a k bit width.

Abstract: An optical communication transmission system including an optical amplifier lumped repeater system of the present invention includes, for the purpose of preventing degradation of the transmission characteristic arising from wavelength dispersion of optical fibers due to raised power of the optical signal, transmission optical fibers provided for all or most of the repeating sections and having wavelength dispersion values set to different values from zero, and optical fibers provided for the individual sections to compensate for the sum of wavelength dispersion of the sections so as to reduce the total wavelength dispersion to zero. The optical fiber for compensation for each section may be replaced by a substitutive compensation element. Alternatively, very small wavelength dispersion which remains due to failure in compensating to zero dispersion may be compensated for using a dispersion equalizer of an electric system in the reception section.

Abstract: It is an object of the invention to provide an optical communication system, which suppresses wave distortions of signal light waves arisen from group velocity dispersion of a transmission line. The optical communication apparatus comprises optical transmitter 100 and optical transmission lines, which consist of optical fibers. The optical transmitter transmits signal and probe light waves simultaneously, and spectrum-inverted wave is generated by nonlinear interaction between the two said waves in the optical nonlinear section. The spectrum inverted wave behaves as a phase conjugated wave, and wave distortion arisen from dispersion of a line can be remarkable decreased when a signal light wave arrives at the terminal of a line. The optical transmitter comprises two light wave sources for signal and probe light waves, and thereby wavelength separation and polarizations of these waves can be stabilized without difficulty.

Abstract: An optical filter having a transmission wavelength to be tuned dependent on light incident angle is rotatively provided in a collimated light path. The optical filter is rotated by the displacement of a piezoelectric actuator by a structure in which the displacement is converted to the rotation of the optical filter. The converting structure comprises a displacement magnifying mechanism for magnifying the displacement to provide the magnified displacement and a motion converting mechanism for converting the magnified displacement to the rotation of the optical filter.

Abstract: A signal light and a clock light which is generated by a clock light generator are propagated through a non-linear optical medium of, for instance, a silica based single mode optical fiber, from which the signal and clock lights and a four-wave mixing light are obtained. One light, for instance, the four-wave mixing light is extracted from the output lights of the non-linear optical medium, and a control signal which is dependent on a time-mean value in power of the extracted light is applied to a voltage controlled oscillator (VCO) for driving the clock light generator. Thus, a clock light which is locked in phase to the signal light is obtained.

Abstract: A frequency stabilization method of a semiconductor laser is provided. A driving current, a forward voltage and an output light power of the laser mounted on a heat sink is detected. A temperature of the heat sink is also detected. A consumption power of the laser is obtained from the driving current and voltage thus detected, providing a relationship between the output light power and the consumption power. The driving current is controlled so that the output light power is kept constant, and the temperature of the heat sink is controlled based on the relationship so that a temperature of an active layer of the laser is maintained. The output light power is kept constant and at the same time, any temperature change of the active layer is cancelled through the temperature control of the heat sink.

Abstract: A method of optical transmission comprises steps of generating a light signal, controlling a wavelength of the light signal in accordance with a correcting signal, and modulating an intensity of the light signal supplied from the light source to generate an output light signal in accordance with a modulating signal. The wavelength change of the light signal generated by the light source coincides with the wavelength change which occurs during the modulating step, so that the wavelength change is cancelled in the output light signal. An optical transmitter used in the method comprises a light source which generates a light signal, a correcting signal generating circuit which supplies the light source with a correcting signal for changing the wavelength of the light signal generated by the light source, and an optical modulator which modulates an intensity of the light signal supplied from the light source to generate an output light signal in accordance with a modulating signal.

Abstract: A transmitter unit (100) including a semiconductor laser (101) as a carrier light exciting source, a biasing source (102) for providing the semiconductor laser with a d.c. biasing current, an external modulator (105) for intensity-modulating an output light of the semiconductor laser according to a transmission signal, and means (107; 210; 510; 701, 702, 703, 704) for causing the external modulator to output only the carrier light and either side-band light. Also provided is a receiver unit (150) including a receiver (151) for square-law detecting the carrier light and the side-band light supplied from the transmitter unit to obtain an electric signal, and a linear filter (152) for equalizing this electric signal. The present invention results in an optical communication apparatus capable of easily equalizing dispersion distortion caused in a transmission path (115) having a large dispersion from a light-intensity modulated light signal transmitted therethrough.

Abstract: A plurality of transmitting signal lights are supplied from a semiconductor laser light source which is modulated by a current having adjusted amplitude and phase injected thereinto in an optical transmitting apparatus. The signal lights are modulated in intensity by a plurality of external modulators, and a time-difference is applied among the signal lights. Thus, the signal lights are combined to provide a transmitting signal light which is propagated through a transmission line. At this time, a frequency component having a low transmission speed is supplied to the transmission line earlier than a frequency component having a fast transmission speed in compliance with a wavelength dispersion property of the transmission line.

Abstract: Supplied with an optical signal from a directly modulated semiconductor laser (11) in an optical transmitter, an optical frequency discriminator (15) converts a frequency modulated component of the optical signal to an intensity modulated component and produces an output optical beam which consists essentially of the intensity modulated component. Preferably, a negative feedback circuit (32, 33) is supplied in effect with the output optical beam representative of mark and space codes and controls the semiconductor laser and/or the optical frequency discriminator to keep the extinction ratio of the output optical signal at an optimum value such that the optical frequency discriminator has a transmissivity of about 90.degree./o for a predetermined one of the mark and space codes and a substantially zero transmissivity for the other of the mark and space codes.

Abstract: In method and apparatus of measuring frequency response in an optical receiving system, a laser light source produces a frequency-modulated laser light which is divided into the first and second lights. The first light is delayed through a longer optical path than that of the second light by a predetermined time, and thereafter the delayed first light and the second light or the original laser light are combined to produce combined light. The frequency response is measured in accordance with output power of beat signal converted from the combined light in regard to frequency of the beat signal.