Abstract: An optical amplifier apparatus for amplifying a wavelength division signal light includes a detector for detecting an inputted wavelength division signal light, a dispersion compensator for compensating for a dispersion of the inputted wavelength division signal light, an optical amplifier for amplifying the inputted wavelength division signal light after compensation by stimulated emission of an optical gain medium including a rare-earth element, a propagation delay detector for detecting a propagation delay time of the wavelength division signal light between the detector and the optical amplifier, and a controller for controlling the gain of the optical amplifier on the basis of the propagation delay time such that the change of the gain of the optical amplifier is adjusted by the propagation delay time.

Abstract: In accordance with the present disclosure, disadvantages and problems associated with polarization dependent effects of a polarization multiplexed optical signal may be reduced through polarization scrambling. In accordance with an embodiment of the present disclosure a method for detecting polarization scrambling of a polarization multiplexed optical signal comprises receiving a polarization multiplexed optical signal associated with an optical network. The polarization multiplexed optical signal including a scrambled polarization orientation, the polarization orientation scrambled according to a scrambling frequency. The method further comprising receiving a polarization signal indicating the polarization scrambling of the received optical signal. The method additionally comprises descrambling the optical signal according to the polarization scrambling as indicated by the polarization signal.

Abstract: A transmission system is provided which multiplexes and transmits synchronous data and asynchronous data, while maintaining the communication quality required of synchronous data and of asynchronous data respectively. A tag having information used to identify the data as synchronous data or as asynchronous data is added to both synchronous data and to asynchronous data. Tags added to each data item are extracted, and based on the information contained in the tag, each data item is identified as synchronous data or as asynchronous data, and synchronous data is transferred to a time-division switch, while asynchronous data is transferred to a packet switch.

Abstract: An optical signal demultiplexing device includes a demultiplexing unit that receives an optical signal multiplexed by an optical time-division system and a synchronization pattern, and demultiplexes the optical signal based on the synchronization pattern. The optical signal demultiplexing device also includes a pulse-width increasing unit that makes optical signals demultiplexed by the demultiplexing unit generate chirp, and increases the pulse widths of the optical signals generating the chirp by passing the optical signals through a wavelength dispersion medium.

Abstract: The optical transmission system modulates backward Raman pump light provided to an optical transmission line on one link side of an uplink and downlink, to thereby transmit a pilot signal for confirming a connection state of the optical transmission line to a node on an upstream side. When the pilot signal is received by the node on the upstream side, the backward Raman pump light provided to the optical transmission link on the opposite link side is modulated to thereby send back a response signal to an own node. Then by confirming receipt of the response signal at the own node, the backward Raman pump light provided to the optical transmission line on the one link side is changed over from a low output state to a high output state.

Abstract: A substrate unit and other substrate unit are mounted with integrated circuits and are connected to a backboard via respective connectors. The substrate unit monitors a signal wave passed between the substrate unit and other substrate unit and detects a delay time and a gain of a reflected wave with respect to a signal wave, performs delay adjustment with respect to a cancellation wave based on the detected delay time, performs gain adjustment with respect to the cancellation wave based on the detected gain, and superimposes the processed cancellation wave on the signal wave thereby canceling the reflected wave.

Abstract: An apparatus including a first interface unit configured to perform frame communication processing with a ring network; a second interface unit configured to perform frame communication processing with a different network; a processing unit configured to convert a frame of a first format from the different network to a frame of a second format; a frame switching unit having at least one port connected to each of the first interface unit, the second interface unit and the processing unit and configured to switch the frame between ports; and a table configured to store frame identification information in correspondence with an output destination port identifier for an output port in the frame switching unit and frame conversion requirement information indicating whether conversion to the frame of the second format is required.

Abstract: An optical transmission apparatus that improves the reliability of system operation by efficiently limiting the line speed of a signal sent from a user with a guard mechanism. An optical branching section makes an optical signal branch in two directions. A through branching line passes an optical signal in its original condition and sends the optical signal as a through optical branch signal. A delay branching line delays an optical signal by a delay amount set and sends the optical signal as a delayed optical branch signal. An optical multiplexing section combines the through optical branch signal and the delayed optical branch signal.

Abstract: In an optical communication system, a pre-compensation is conducted for an influence of a polarization dispersion and a polarization dependent loss, which an optical signal transmitted from a transmitter station to a receiver station receives from a communication channel, at a transmitter station. The influence of the polarization dispersion and the polarization dependent loss from the transmission channel is cancelled when the receiver station receives the optical signal.

Abstract: There is provided an optical transmission apparatus including: a plurality of wavelength selective switches including input ports, a transmission port, and monitor port used to output a light switched so that the light from the input port is monitored; a multiplexer to combine the lights output from the transmission ports of the plurality of wavelength selective switches; a monitor to monitor whether a same wavelength of the light output from the monitor port exists in wavelengths of the lights combined by the multiplexer; and a controller to control the wavelength selective switch so as to output, from the transmission port, the light switched to the monitor port in case that the same wavelength of the light output from the monitor port is absent in wavelengths of the lights combined by the multiplexer, based on a monitor result by the monitor.

Abstract: In a receiving-side printed circuit board, a reflected-waveform analyzing unit analyzes a reflected wave generated in a transmission line on a backplane along with transmission of a signal from a transmitting-side printed circuit board, and acquires waveform data that indicates a waveform of the reflected wave. An input signal identifying unit calculates a size of the reflected wave that is currently received based on the waveform data and data on previously received signals. The input signal identifying unit corrects a threshold value by the calculated size, and identifies a state of a bit indicated by the signal from the transmitting-side printed circuit board.

Abstract: An optical communication system includes an optical transmission terminal including a first transmitter for transmitting an optical signal, and a second transmitter for transmitting information that indicates the first transmitter transmitting the optical signal; and an optical receiving terminal including an optical receiver for receiving the optical signal and the information transmitted from the first and second transmitter, respectively, a storage device for storing a power value of the optical signal monitored in response to receipt of the information transmitted from the second transmitter, and a fault detector for detecting fault of the optical signal by continuously monitoring a power value of the optical signal received by the optical receiver in comparison with the power value stored in the storage device.

Abstract: In an optical transmission device, when wavelength division multiplexed light formed from signals of a plurality of wavelengths are received, an optical signal of one wavelength comprised in this wavelength division multiplexed light is planarized and non-signal light of the same wavelength is reproduced. The reproduced light is modulated with a transmission data string, an optical signal is generated, and a wavelength division multiplexed light comprising the generated optical signal is transmitted.

Abstract: An optical amplifier apparatus for amplifying a wavelength division signal light includes a detector for detecting an inputted wavelength division signal light, a dispersion compensator for compensating for a dispersion of the inputted wavelength division signal light, an optical amplifier for amplifying the inputted wavelength division signal light after compensation by stimulated emission of an optical gain medium including a rare-earth element, a propagation delay detector for detecting a propagation delay time of the wavelength division signal light between the detector and the optical amplifier, and a controller for controlling the gain of the optical amplifier on the basis of the propagation delay time such that the change of the gain of the optical amplifier is adjusted by the propagation delay time.

Abstract: A transmission-path-type specifying apparatus includes an optical filter that extracts a plurality of different wavelength components from light including wavelength components occurring at the time of communication; an optical switch that simultaneously transmits same pulse signals superposed on light of the extracted wavelength components. The apparatus also includes an ASE modulation controlling unit that obtains a delay-time difference among the transmitted pulse signals when arriving at a destination via a transmission path; a characteristic-value calculating unit that calculates a characteristic value of the transmission path corresponding to a reference time varied depending on the obtained delay-time difference and a type of the transmission path; and a fiber-type determining unit that specifies the type of the transmission path based on the calculated characteristic value.

Abstract: A dispersion compensating method for carrying out automatic level control with the use of target output power and an ASE correction value corresponding to the number of wavelengths to multiplex and making output power of a wavelength multiplexed signal constant, comprising the steps of: switching into automatic gain control in which the output power of the wavelength multiplexed signal is made constant, to carry out increase/decrease of the wavelengths to multiplex; varying a dispersion compensating amount based on the increase/decrease of the wavelengths by the automatic gain control; calculating an ASE variation amount due to the change in the dispersion compensating amount; and reflecting the ASE variation amount on the ASE correction value and switching into the automatic level control.

Abstract: An optical signal multiplexing device includes a delay-amount adjusting unit that converts wavelengths of optical signals to be multiplexed when the optical signals are obtained, and adjusts delay amounts of the optical signals by passing the wavelength-converted optical signals through waveguides that generate propagation delays corresponding to the wavelengths in the optical signals. The optical signal multiplexing device also includes a waveform-degradation compensation unit that compensates for degradation of a waveform of the optical signals while keeping a difference of propagation delay times between the optical signals delay amounts of which are adjusted by the delay-amount adjusting unit.

Abstract: A power-down delay unit for delaying cutoff of a voltage is provided in a power supply line which supplies electrical power to an optical module of a transponder unit for each optical wavelength. The power-down delay unit assigns different delays for each wavelength. The length of the delay is a time required by an AMP unit to change from an ALC mode to an AGC mode or longer. When the power sources for supplying electrical power to the transponder units becomes faulty and outputs of several wavelengths are simultaneously going to stop, the power-down delay unit delays cutoff of the supply voltage to the optical modules by keeping supply voltage for a while to the optical modules on behalf of power sources enabling the optical modules to operate after the power sources shutdown, so that the actual optical signals gradually stop one by one.

Abstract: One of two optical fibers connecting communication stations is used for transmitting multiple wavelength light supplied from a multiple wavelength light source supply apparatus, and the other for a bidirectional communication using optical signals of respective wavelengths generated from the multiple wavelength light. Alternatively, a transmission of multiple wavelength light and a bidirectional communication using the optical signals are enabled by only one optical fiber.

Abstract: In a receiving-side printed circuit board, a reflected-waveform analyzing unit analyzes a reflected wave generated in a transmission line on a backplane along with transmission of a signal from a transmitting-side printed circuit board, and acquires waveform data that indicates a waveform of the reflected wave. An input signal identifying unit calculates a size of the reflected wave that is currently received based on the waveform data and data on previously received signals. The input signal identifying unit corrects a threshold value by the calculated size, and identifies a state of a bit indicated by the signal from the transmitting-side printed circuit board.