Abstract: An optical transmission apparatus, an optical repeater using the optical transmission apparatus, and an optical cross-connect equipment for controlling switches depending on supervisory information, comprising: a doped fiber for amplifying an optical signal of wavelength Od; a wavelength multiplexer for outputting a pumping light to the doped fiber; a wavelength multiplexer for multiplexing an amplified optical signal and a supervisory optical signal to as to output it to an optical fiber at downstream side; a pumping and supervisory light source; an optical coupler for distributing the light from the light source at a ratio of N:1 to the wavelength multiplexers; and a driver for controlling the light source by adding the supervisory information and a direct current signal.

Abstract: In an optical switching apparatus having redundantly-arranged optical switches, a route switching operation mode, an autonomic redundant switching operation mode and a compulsory redundant switching operation mode are discriminated from one another so that these operation modes are prevented from being executed at the same time, and also proper mask processing is performed at every switching operation mode. Therefore, emission of an undesired alarm and thus occurrence of malfunction when each switching operation is carried out can be prevented.

Abstract: An optical communication network system is disclosed, which includes an optical switching apparatus. The optical switching apparatus includes an optical switch for switching and setting routes of an optical signal without being converted, a control unit for instructing the optical switch to execute a route switching operation, and a performance monitor for detecting performance of the optical signal having a route set by the optical switch. The performance monitor issues an alarm when the performance detected is deteriorated from predetermined performance. The control unit includes an alarm masking unit for masking the alarm issued from the performance monitor at least for a predetermined masking period from a starting time of a switching operation by the optical switch, and thus preventing the alarm from being issued.

Abstract: The optical switching equipment is basically configured as a single configuration without protection as a basic unit and to split the optical signal into one signal passing through the equipment and the other signal to be added and dropped in the equipment and execute the adding and dropping process in a redundant portion. The optical transport network is configured to locate a plurality of optical switching equipments and optical transmission routes so as to allow the optical signals processed in the equipment for adding the optical signals to pass through the different optical transmission routes and equipments respectively. The optical signal allowed to pass through the equipment is processed in the single configuration portion of the equipment. The setting of the routes of the optical switching equipment and the optical transmission route makes it possible for the overall optical transport network to transmit the redundant optical signal.

Abstract: In order to provide a small-sized and compact optical switch of 1×4 type. Two movable optical fibers are fixed on a substrate by a fixing block disposed in a middle portion of the fibers. Two movable blocks made of a soft magnetic body are mounted to the both ends of the movable optical fibers. Two soft magnetic fixing blocks are arranged on the substrate for fixing one optical fiber so as to oppose to one of the movable block, and for fixing four optical fibers so as to oppose to the movable block, respectively. Two movable blocks can be independently moved with respect to the respective fixing blocks by means of actuators. Further, it is possible to detect a position of each movable block with respect to the fixing block by means of detecting electrodes.

Abstract: An optical transmission apparatus, an optical repeater using the optical transmission apparatus, and an optical cross-connect equipment for controlling switches depending on supervisory information, comprising: a doped fiber for amplifying an optical signal of wavelength Od; a wavelength multiplexer for outputting a pumping light to the doped fiber; a wavelength multiplexer for multiplexing an amplified optical signal and a supervisory optical signal to as to output it to an optical fiber at downstream side; a pumping and supervisory light source; an optical coupler for distributing the light from the light source at a ratio of N:1 to the wavelength multiplexers; and a driver for controlling the light source by adding the supervisory information and a direct current signal.

Abstract: A light emitted from the supervisory light source is supplied to the input port of any one of a plurality of switching sections provided in the optical switching device. A light emitted from the output port of the switching section is converted into electric signals and then compared with the threshold value by a supervisory receiver. The supervisory control circuit discriminates the state of connection at each switching section in the optical switching device according to the compared result obtained by the supervisory receiver, whereby each switching section in the optical switching device is supervised.

Abstract: Variable (coupling ratio) optical couplers 3-0 and 6-0 each have ports of two inputs and two outputs, and the coupling ratio of inputted light is variably controlled by drive circuits 4-1 and 7-1. In the optical 1+1 switching structure, the coupling ratio of the variable (coupling ratio) optical coupler 3-0 is controlled to be 50%:50%. The variable (coupling ratio) optical coupler 6-0 is controlled to have the coupling ratio of 100%:0% or 0%:100%. In the optical 1:1 switching structure, the coupling ratios of the variable (coupling ratio) optical couplers 3-0 and 6-0 are controlled to be 100%:0% or 0%:100%. When a performance monitor (0) 9-0 detects signal degradation, signal interruption, and the like, the system controller 1-0 sends an instruction signal and the control circuits 20-0 and 21-0 output control signals for controlling coupling ratios of the variable (coupling ratio) optical couplers 3-0 and 6-0, respectively.

Abstract: An optical transmission apparatus, an optical repeater using the optical transmission apparatus, and an optical cross-connect equipment for controlling switches depending on supervisory information, comprising: a doped fiber for amplifying an optical signal of wavelength &lgr;d; a wavelength multiplexer for outputting a pumping light to the doped fiber; a wavelength multiplexer for multiplexing an amplified optical signal and a supervisory optical signal to as to output it to an optical fiber at downstream side; a pumping and supervisory light source; an optical coupler for distributing the light from the light source at a ratio of N:1 to the wavelength multiplexers; and a driver for controlling the light source by adding the supervisory information and a direct current signal.

Abstract: The method and system are disclosed for reducing an optical surge in an optical data communication system that includes at least pair of optical lines, optical switches and optical amplifiers to maintain high reliability in data transmission. The optical surge is substantially reduced or suppressed by assuring a proper timing of the optical switch operation based upon a predetermined elapsed time or a predetermined safe amplification gain of the optical amplifier.

Abstract: In order to provide a small-sized and compact optical switch of 1×4 type. Two movable optical fibers are fixed on a substrate by a fixing block disposed in a middle portion of the fibers. Two movable blocks made of a soft magnetic body are mounted to the both ends of the movable optical fibers. Two soft magnetic fixing blocks are arranged on the substrate for fixing one optical fiber so as to oppose to one of the movable block, and for fixing four optical fibers so as to oppose to the movable block, respectively. Two movable blocks can be independently moved with respect to the respective fixing blocks by means of actuators. Further, it is possible to detect a position of each movable block with respect to the fixing block by means of detecting electrodes.

Abstract: An optical signal switching apparatus that maintains an optical switch to a specified state even when noise is generated during the turning on and/or off of power to an optical switch control unit which controls the optical switch. The optical switch control unit includes an optical switch driving unit, a power supply and a power supply surveillance unit. When a specified condition of the power supply is not satisfied, a control signal is generated by the power supply surveillance unit. Upon detection of the control signal the optical switch driving unit, fixes the state of the optical switch to a previously set state without regard to the input to the optical switch driving unit.

Abstract: Upon receiving a check request 300 from a management system 250, a controller 230 sends a switching request 310 to an optical switch driver 165. The optical switch driver 165 sends a drive signal 320, and an optical switch 160 switches from a first transmission line 120 to a second transmission line 130. A receive signal performance monitor 190 sends a sensing result 330 for the second transmission line 130 to the controller 230. The controller 230 sends a switch-back request 340, and the optical switch 160 switches from the second transmission line 130 to the first transmission line 120. Based on information from the receive signal performance monitor 190, a first transmission line optical sensor 210, and a second transmission line optical sensor 220, the controller 230 performs a sensing result save 360 in a memory 240. A management system 250 saves a results report 400 from the controller 230 in a memory device.

Abstract: Variable (coupling ratio) optical couplers 3-0 and 6-0 each have ports of two inputs and two outputs, and the coupling ratio of inputted light is variably controlled by drive circuits 4-1 and 7-1. In the optical 1+1 switching structure, the coupling ratio of the variable (coupling ratio) optical coupler 3-0 is controlled to be 50%:50%. The variable (coupling ratio) optical coupler 6-0 is controlled to have the coupling ratio of 100%:0% or 0%:100%. In the optical 1:1 switching structure, the coupling ratios of the variable (coupling ratio) optical couplers 3-0 and 6-0 are controlled to be 100%:0% or 0%:100%. When a performance monitor (0) 9-0 detects signal degradation, signal interruption, and the like, the system controller 1-0 sends an instruction signal and the control circuits 20-0 and 21-0 output control signals for controlling coupling ratios of the variable (coupling ratio) optical couplers 3-0 and 6-0, respectively.

Abstract: A method for restoration from a fault in a communication network formed by interconnecting a plurality of nodes including at least one set of node equipment each including a line terminal equipment and an optical cross-connect equipment, via a plurality of transmission lines using optical fibers. According to this method for restoration from a fault, if a line terminal equipment of at least one set of node equipment has detected a fault in an optical fiber under communication, it gives a command functioning as trigger for optical fiber change-over to an optical cross-connect equipment included in the node equipment. Upon receiving this command functioning as the trigger, the optical cross-connect equipment exchanges change-over control information indicating optical switch setting situation between it and an optical cross-connect equipment included in another node equipment, and forms a restoration route.

Abstract: A medium-scale IP telecommunications network is configured in a low-cost optical network with good reliability and expandability. A physical configuration example has a center node 2-1 and eight local nodes 2-11 through 2-18 connected in one OADM ring 2-21/2-22. The logical configuration is a star configuration with the central node 2-1 at its origin with all traffic passing through the center node 2-1. The local nodes 2-11 through 2-18 are connected to the central node 2-1 by wavelength-unit optical channels or optical paths &lgr;1 through &lgr;8. Channels are added as required. Initially, for example, the center node 2-1 and the local node 2-5 are connected by &lgr;5, but &lgr;13 can added when the need arises. Since the logical star network is limited to approximately two add/drop optical channels at local nodes, costs are reduced by using inexpensive filters (e.g.

Abstract: An optical signal switching apparatus that maintains an optical switch to a specified state even when noise is generated during the turning on and/or off of power to an optical switch control unit which controls the optical switch. The optical switch control unit includes an optical switch driving unit, a power supply and a power supply surveillance unit. When a specified condition of the power supply is not satisfied, a control signal is generated by the power supply surveillance unit. Upon detection of the control signal the optical switch driving unit, fixes the state of the optical switch to a previously set state without regard to the input to the optical switch driving unit.

Abstract: A wavelength division multiplex communication system comprises a head station (2) and a plurality of terminal stations (1) interconnected by an optical fibre cable (3). The head station (2) transmits continuous wave modulated wavelengths (.lambda..sub.1 -.lambda..sub.k), and a signalling wavelength (.lambda..sub.0) which is used to indicate, in each time slot, which wavelengths in the following time slot are available for transmission. Each terminal station (1) is arranged to receive the signalling wavelength, to determine therefrom whether the next time slot contains any data packets for that terminal station and, if so, to receive the packets. The terminal station (1) is arranged, if it has a data packet to transmit, to determine from the signalling wavelength whether the next time slot already contains data packets for the destination station and, if so, to avoid data collision by not transmitting its own data packet. The terminal station (1) then determines a free wavelength (.lambda..sub.

Abstract: A wavelength division multiplex communications system has a head station and a plurality of terminal stations interconnected by an optical fiber cable. The head station transmits CW modulated wavelengths (.lambda.-.sub.1 -.lambda..sub.k), and a signalling wavelength (.lambda..sub.0) which is used to indicate, in each time slot, which wavelengths in the following time slot are available for transmission. Each terminal station is arranged to receive the signalling wavelength (.lambda..sub.0), to determine therefrom whether the next time slot contains any data packets for that terminal station and, if so, to receive the packets. Each terminal station is arranged, if it has a data packet to transmit, to determine from the signalling wavelength (.lambda..sub.0) whether the next time slot already contains data packets for the destination station and, if so, to avoid data collision by not transmitting its own data packet. The terminal station then determines a free wavelength (.lambda..sub.

Abstract: An optical repeater for realizing transmission of supervisory information of an optical fiber transmission system without the output power of an optical fiber amplifier being reduced, wherein a supervisory optical transmitter and optical receiver with a wavelength which is similar to the wavelength of the pumping light source of the optical fiber amplifier are mounted, and on the input side of the optical repeater, pumping light is multiplexed in the forward direction and a supervisory optical signal, which is multiplexed in wavelength and transmitted, is demultiplexed simultaneously by the first wavelength multi- and demultiplexer and they are received by the supervisory optical receiver, and on the output side of the optical repeater, pumping light is muitiplexed in the reverse direction and a supervisory optical signal outputted from the supervisory optical transmitter is multiplexed by the second wavelength multi- and demultiplexer.