Abstract: Disclosed is an optical signal repeating and amplifying device which has: an optical amplifier which amplifies an optical signal to be input thereto and then outputs it; and an optical filter means through which only one wavelength light of the optical signal to be output from the optical amplifier is passed. Also disclosed is an optical level adjusting device which has: an optical demultiplexer which demultiplexes a wavelength-multiplexed optical signal into a plurality of wavelength lights; a plurality of optical attenuators which attenuate separately the demultiplexed plurality of wavelength lights to be output from the optical demultiplexer; and an optical multiplexer which multiplexes the attenuated wavelength lights to be output from the plurality of optical attenuators into a wavelength-multiplexed optical signal and output it.

Abstract: To optimize the number of optical gate switches required by an optical switching apparatus which comprises an optical space switch and wavelength selectors, the following process as a preliminary process of introducing optical signals into the optical space switch, is carried out. In detail, the preliminary process is optically converting the optical signals in relation to the number of input ports of the optical space switch, by optically processing the optical signals. As the results, the number of processed optical signals responding to the input ports and the processed number of wavelengths of each processed optical signal is equal to each other, and thereby, the optimization is achieved.

Abstract: An optical packet exchange apparatus and an optical switch in which search for a connection pattern between an input unit devoid of a packet to be transmitted and an output unit devoid of a packet to be received is reduced to enable fast switch control even in cases wherein the number of channels of the exchange apparatus is increased or network speed is higher. A plurality of input units, a plurality of output units and an optical switch are provided. Each input unit includes an input buffer unit, a parallel/serial conversion unit, an electrical/optical conversion unit, and a dummy packet insertion unit for sending a dummy packet if there is no packet to be transmitted. Each output unit includes an exchange counterpart contention resolution unit for controlling the exchange counterpart, an optical/electrical conversion unit, a serial/parallel conversion unit, and a packet eliminating unit. The exchange counterpart contention resolution unit controls the packet eliminating unit to eliminate a dummy packet.

Abstract: An optical packet exchange apparatus and an optical switch in which search for a connection pattern between an input unit devoid of a packet to be transmitted and an output unit devoid of a packet to be received is reduced to enable fast switch control even in cases wherein the number of channels of the exchange apparatus is increased or network speed is higher. A plurality of input units, a plurality of output units and an optical switch are provided. Each input unit includes an input buffer unit, a parallel/serial conversion unit, an electrical/optical conversion unit, and a dummy packet insertion unit for sending a dummy packet if there is no packet to be transmitted. Each output unit includes an exchange counterpart contention resolution unit for controlling the exchange counterpart, an optical/electrical conversion unit, a serial/parallel conversion unit, and a packet eliminating unit. The exchange counterpart contention resolution unit controls the packet eliminating unit to eliminate a dummy packet.

Abstract: Disclosed is an optical network which has: wavelength tunable optical transmitters of number MN, where N is an integer of two or more, each of which outputs an optical signal with arbitrary one of M wavelengths &lgr;1, &lgr;2, . . . , &lgr;M, where M is an integer of two or more, that are different from one another; a MN×N optical switch whose input ports are connected to the respective wavelength tunable optical transmitters of number MN, and which allows optical signals input to different input ports to be output form its same output port; 1×M optical wavelength demultiplexers of number N which output demultiplexing optical signal with wavelengths &lgr;1, &lgr;2, . . . , &lgr;M input from output ports of the MN×N optical switch into each wavelength; and optical receivers of number MN which receive optical signals input from the 1×M optical wavelength demultiplexers of number N.

Abstract: The first present invention provides an optical switch including the following elements. At least a plurality of optical transmission lines are provided for transmissions of optical signals. Each of the at least plurality of optical transmission lines have a least an impurity doped fiber. At least an excitation light source is provided for emitting an excitation light.

Abstract: Optical regenerative relay amplifier 102 has a function for monitoring the power of optical signals from an optical fiber 101, and issuing an optical signal trouble detection signal (AIS (Alarm Indication Signal)) for shutting down the optical power in case that optical signal inputs are lost, and notifying the trouble, and optical ADMs 103 have a wavelength path selecting function, a wavelength path bundle function, and a wavelength path trouble or quality monitoring function in addition to an AIS issue function, and the optical cross-connect systems 104 have an AIS issue function, a function for monitoring a trouble or quality deterioration of optical signals for every wavelength path, a wavelength path grooming function, and a wavelength path protection function, and the terminal stations 105 transmit and receive services by optical signals having predetermined wavelengths, and monitoring a trouble or quality deterioration of optical signals for every wavelength path is conducted without depending on signa

Abstract: An optical wavelength division coupler 11 wavelength-divides a wavelength multiplexed light to respective wavelength lights each of which is dropped to an optical gate switch 15-i (i=1˜n) and a light receiver 13-i by an optical coupler 12-i and supplied to an optical light fault monitor 14 through the light receiver 13-i. When the optical signal deterioration monitor 14 detects an optical loss of wavelength (OLOW), an optical loss of signal (OLOS) or an optical signal degrade (OSD) in wavelength lights processed by the optical coupler 12-i as a fault detection signal in an optical layer, a controller 19 controls the optical gate switch 15-i to cut off wavelength light passing therethrough and sends an optical alarm indication signal (AIS-O) to a downstream side. Therefore, when a loss of signal is detected by the light receiver 13-i, the optical signal deterioration monitor 14 can know the alarm indication signal (AIS) from the upstream side, removing the necessity of special hardware therefor.

Abstract: Disclosed is an optical signal repeating and amplifying device which has: an optical amplifier which amplifies an optical signal to be input thereto and then outputs it; and an optical filter means through which only one wavelength light of the optical signal to be output from the optical amplifier is passed. Also disclosed is an optical level adjusting device which has: an optical demultiplexer which demultiplexes a wavelength-multiplexed optical signal into a plurality of wavelength lights; a plurality of optical attenuators which attenuate separately the demultiplexed plurality of wavelength lights to be output from the optical demultiplexer; and an optical multiplexer which multiplexes the attenuated wavelength lights to be output from the plurality of optical attenuators into a wavelength-multiplexed optical signal and output it.

Abstract: A bit synchronization circuit operates at high speed range as high as Gb/s or higher and can establish synchronization within 10 bits with rejecting jitter to permit accurate bit synchronization. The bit synchronization circuit thus generates a plurality of clocks having mutually different phases in synchronism with an input reference clock. A phase relationship between a plurality of clocks and an input data to be decided is discriminated by a phase comparator circuit. The clock having optimal phase relationship, namely clock having level transition timing having at a substantially center portion of mutually adjacent level transition timing of the input data, is determined by a phase determination circuit. An decision circuit and selector are provided for deciding input data at the level transition timing of the determined clock.

Abstract: There is disclosed an array type space optical switch 10 of the present invention, in which each one end of optical fibers 101a to 104a, 101b to 104b is fixed to support members 105a, 105b. The optical fibers 101a and 101b form one pair, and have end surfaces opposite to each other, and the optical fibers 102a and 102b form one pair, and have end surfaces opposite to each other. Moreover, the optical fibers 103a and 103b form one pair, and have end surfaces opposite to each other, and the optical fibers 104a and 104b form one pair, and have end surfaces opposite to each other. A space propagation part 200 is formed between the end surfaces of the optical fibers 101a to 104a and 101b to 104b. An interrupting plate is inserted to or extracted from the space propagation part 200.

Abstract: The first present invention provides an optical switch including the following elements. At least a plurality of optical transmission lines are provided for transmissions of optical signals. Each of the at least plurality of optical transmission lines have at least an impurity doped fiber. At least an excitation light source is provided for emitting an excitation light.

Abstract: An optical wavelength selector is provided that selects WDM channels from WDM optical signal and outputs each WDM channels from a plurality of ports. WDM optical signal in which m×n WDM channels are multiplexed is divided into n WDM channel groups and outputted by means of one wavelength-division demultiplexer. One WDM channel group is selected from the n WDM channel groups by means of n optical gate switches. The selected WDM optical signal is then separated into m WDM channels by wavelength and outputted by means of an optical wavelength router. As a result, m WDM channels of a specific WDM channel group can be received by m optical receivers.

Abstract: A storage circuit defines a first field for storing first header bits of a first payload signal of a first data unit, a second field, and a third field for storing signal first payload signal. The first header bits are equal in number to second header bits of a second payload signal of a second data unit. A division circuit divides the first header bits by a generator polynomial to produce a first error check code. The same generator polynomial is used to divide the second header bits to produce a second error check code. A remainder of division of hypothetical header bits by the generator polynomial is summed to the first error check code to produce a sum which is inserted into the second field of the storage circuit. The hypothetical header bits are greater in number than a total number of bits in the first and second fields, so that the first and second data units can be distinguished from each other by different error check results of the first and second data units.

Abstract: A wavelength multiplexing optical transmitter 100 comprises a laser driving circuit 102 for driving a multi-mode oscillation semiconductor laser 101 and an optical filter 103 for filtering an optical output from said multi-mode oscillation semiconductor laser 101. An electric signal in a desired code form is input in the wavelength multiplexing optical transmitter 100. The electric signal input into the wavelength multiplexing optical transmitter 100, after being introduced into the laser driving circuit 102 in the wavelength multiplexing optical transmitter 100, executes a direct current modulation of the multi-mode oscillation semiconductor laser 101. The multi-mode oscillation semiconductor laser 101 outputs optical signals in response to the electric current input from the laser driving circuit 102.

Abstract: An optical wavelength selector is provided that selects WDM channels from WDM optical signal and outputs each WDM channels from a plurality of ports. WDM optical signal in which m×n WDM channels are multiplexed is divided into n WDM channel groups and outputted by means of one wavelength-division demultiplexer. One WDM channel group is selected from the n WDM channel groups by means of n optical gate switches. The selected WDM optical signal is then separated into m WDM channels by wavelength and outputted by means of an optical wavelength router. As a result, m WDM channels of a specific WDM channel group can be received by m optical receivers.

Abstract: Disclosed is an optical network which has a plurality of optical division and insertion nodes and one or a plurality of hub (central) nodes which are circularly connected by using an optical transfer system where a clockwise or counterclockwise data transfer is conducted by using a plurality of optical fibers or an optical wavelength-multiplexing technique; wherein the hub (central) node and the plurality of division and insertion nodes individually use signal lights with wavelengths different from each other and are provided with a transmission system composed of two or more clockwise or counterclockwise independent paths, and the optical division and insertion node selects one of signals obtained from the two or more paths.

Abstract: A network node comprises a cross-connect switch and a single signal quality monitor connected to one of the output ports of the cross-connect switch. The switch is controlled by a processor to establish connections. The processor is responsive to a request message from another network node for causing the switch to establish a connection between one of the input ports of the switch specified by the request message and the signal quality monitor and returns a reply message indicating a quality level of a signal appearing at the input port. A switched telecommunications network, such as Internet, may be used for transmission of the request and reply messages. Alternatively, the request and reply messages may be multiplexed with traffic signals.

Abstract: An optical communication network node apparatus including input terminals 111 to 11n, 1:2 optical branch units 121 to 12n, a pass-through optical switching network d101, 2:1 optical connectors 151 to 15n, output terminals 171 to 17n, a drop optical switching network 102, output interfaces 13-1 to 13-mn, input interfaces 14-1 to 14-mn and an insert optical switching network. Accordingly, in the optical communication network node apparatus, various types of optical switching networks are separated from one another and each optical switching network supports only a necessary switching state, so that the number of optical switch elements can be reduced.

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.