Abstract: A wavelength division multiplexed optical signal transmission method, a wavelength division multiplexed optical signal transmission system and an optical repeater enabling the number of wavelengths to be detected without error even when optical noise is caused in the optical repeater and such functions as adjustment and monitoring of the level of a wavelength division multiplexed optical signal to be performed properly. An optical repeater processes controlled optical signals of different wavelengths individually based on a control optical signal that contains wavelength number information indicating the total number of wavelengths and the presence or absence of a controlled optical signal with respect to each wavelength. Thus, even when optical noise is caused in the optical repeater, the number of wavelengths can be detected without error and such functions as adjustment and monitoring of the level of a wavelength division multiplexed optical signal can be performed properly.

Abstract: In a wavelength-division-multiplexing optical transmission system in which optical-node apparatuses that perform relay transmission of wavelength-division-multiplexed light are located at specified nodes in a main optical transmission path, an optical amplifier switches level control to constant-gain control when there is a notification of a change in the number of multiplexed wavelengths, and then after a specified amount of time restarts level control so that the level becomes a target level that corresponds to the actual number of wavelengths.

Abstract: A method of dynamically adjusting an optical module in an optical system including a plurality of transmission channels includes the following steps: measuring the quality of the optical signal at the output of the system as defined by an error function, varying an optical parameter of at least one module of the system, measuring a differential error introduced by each variation on the error function of the optical signal at the output of the system, estimating an operating point of the system corresponding to an expected reduction of the error function, and adjusting a parameter of an optical module toward the operating point of the system.

Abstract: An optical amplifier may be quickly returned from a shutdown state to a regular state after getting recovery information of a fault. Gain setting by ASE is conducted to the repeaters on the up-stream side during the shutdown state, by outputting ASE light with the same intensity as the WDM signal. Accordingly, before realizing the recovery of shutdown, the gain setting is completed with the light whose intensity is within the safe criterion. After realizing the recovery of shutdown, the optical transmission system can be returned quickly to the regular operating state after recovery of shutdown state.

Abstract: Terminal equipment of a wavelength division multiplexing optical transmission system is provided with a monitoring apparatus for monitoring optical transmission paths with an OTDR. For this monitoring, OTDR probe lights of different wavelengths are allocated to optical fibers and optical amplifier-repeaters, which are elements constituting the optical transmission paths. Further, different wavelengths are allocated to OTDR probe lights between the up link and the downlink. Such a wavelength as makes the wavelength dispersion over the optical transmission paths negative (usually the shorter wavelength side than the zero dispersion wavelength of the optical transmission paths) is allocated to the OTDR probe light for optical fiber monitoring, and a wavelength longer than 1550 nm is allocated to the OTDR probe light for optical amplifier-repeater monitoring.

Abstract: The disclosed technology provides a dynamic interconnection system which allows to couple a pair of optical beams carrying modulation information. In accordance with the disclosed technology, two optical beams emanate from transceivers at two different locations. Each beam may not see the other beam point of origin (non-line-of-sight link), but both beams can see a third platform that contains the system of the disclosed technology. Each beam incident on the interconnection system is directed into the reverse direction of the other, so that each transceiver will detect the beam which emanated from the other transceiver. The system dynamically compensates for propagation distortions preferably using closed-loop optical devices, while preserving the information encoded on each beam.

Abstract: An optical transmission apparatus comprising a first detector for detecting the power of the supervisory signal light separated from received wavelength-division multiplexed signal lights; a second detector for detecting the power of the wavelength-division multiplexed signal lights after the separation of the supervisory signal light; a gain-controlled type optical amplifier for amplifying the wavelength-division multiplexed signal lights; an optical attenuator coupled to the amplifier; and a control unit for controlling the optical amplifier and the optical attenuator so as to keep the output level of the wavelength-division multiplexed signal lights to a predetermined target value, wherein the control unit restrains automatic output level control by the optical attenuator when the supervisory signal light power fluctuates within its permissible range and fluctuations in the signal light power have deviated from its permissible range.

Abstract: A sub signal modulation apparatus, with the intention of stabilized transmission of a sub signal superimposed on main signal light irrespective of the intensity of the main signal light when used in a general-purpose main signal transmitter, including a sub signal outputting unit; a variable optical attenuator for variably attenuating main signal light, into which the main signal has been modulated, at a response speed lower than ½ of a speed of the main signal; an attenuation determining unit for determining, in accordance with the sub signal output from the sub signal outputting unit, an attenuation of the variable optical attenuator for the main signal light; and a stabilizing controller for controlling the attenuation determining unit such that an amplitude of the attenuation of the variable optical attenuator is stabilized to have a constant ratio to a mean intensity of the main signal light.

Abstract: The invention pertains to optical fiber transmission systems, and is particularly relevant to optical transport systems employing optical amplifiers. In particular the invention teaches an apparatus and method that allows cost effective co-directional operation of an optical amplifier to support full duplex traffic on a single fiber, and the design of an optical fiber transmission system based on this optical amplifier technology.

Abstract: There is provided a method of, and apparatus for, regulating radiation component (wavelength channel) power in a wavelength division multiplexed (WDM) optical communications system (10). The system (10) comprises a plurality of nodes (20) interconnected through optical waveguides (30, 40) (optical fibers). The method is characterised by: passing one or more tokens (300) around the system from node to node; adjusting nodal settings (150, 170), such as optical attenuation, applied at each node to regulate the power of WDM radiation components at the node in response to receiving one or more tokens; and repeating the method until WDM radiation component power within the system is substantially regulated.

Abstract: In each of a plurality of submarine observation apparatus (1 to n), a branching unit (63) branches fixed-wavelength light (?1) from an incoming wavelength-multiplexed light signal. An observation signal modulating unit (64) modulates the intensity of the branched fixed-wavelength light (?1) with observation information multiplexed by an observation signal multiplex unit (61). A combining unit (65) combines light signals (?2) to (?n) passing through the branching unit (63) and the fixed-wavelength light (?1a) modulated by the observation signal modulating unit (64) into a composite light signal, and outputs it to an optical fiber (12a). Therefore, in each of the plurality of submarine observation apparatus (1 to n), there is no necessity for providing a wavelength-division-multiplexing-transmission optical transmitter which requires high wavelength stability.

Abstract: An apparatus for shared optical performance monitoring (OPM) is provided. A wavelength sensitive device receives light at an input port and routes it wavelength selectively to a set of output ports. To perform optical performance monitoring on the output ports, a monitoring component of each output signal is extracted, and these monitoring components are then combined. A single OPM function is then performed on the combined signal. However, with knowledge of the wavelengths that were included in each output signal, a virtual OPM function can be realized for each output port. The per port functionality can include total power per port, power per wavelength per port, variable optical attentuation, dynamic gain equalization, the latter two examples requiring feedback.

Abstract: The invention pertains to optical fiber transmission systems, and is particularly relevant to optical transport systems employing optical amplifiers. In particular the invention teaches an apparatus and method that allows cost effective co-directional operation of an optical amplifier to support full duplex traffic on a single fiber, and the design of an optical fiber transmission system based on this optical amplifier technology.

Abstract: A method for determining gain for an optical signal includes measuring a first power level that is an output power level of an optical signal at a first optical node, communicating the optical signal to a second optical node, and communicating the first power level to the second optical node in an optical supervisory channel of the optical signal. The method further includes receiving the optical signal at the second optical node, measuring a second power level of the optical signal at the second optical node, and determining a gain for the optical signal based on the first and second power levels.

Abstract: A regenerator for restoring the originally encoded optical phase of a differential-phase-shift-keyed signal. In an embodiment, the regenerator simultaneously provides limiting amplification and reduces amplitude noise based on a phase-sensitive optical amplifier that combines a weak signal field of a degraded input data with a strong pump field supplied by a local oscillator in a nonlinear interferometer. The two fields interact through degenerate four-wave mixing, and optical energy is transferred from the pump to the signal and vice versa. The phase sensitive nature of the optical gain leads to amplification of a specific phase component of the signal, determined by the input pump-signal phase difference and the incident signal phase is restored to two distinct states, separated by 180° according to the original encoding. Simultaneously, gain saturation of the pump wave by the signal wave results in limiting amplification of the signal wave for removing signal amplitude noise.

Abstract: An optical transmission system includes an optical fiber transmission line, one or more optical repeating apparatuses, an optical receiving apparatus, and a transferring route for transferring a supervisory signal based on a quality deterioration of an optical signal detected by the optical receiving apparatus to the optical repeating apparatus from the optical receiving apparatus. The optical repeating apparatus includes an optical level variation detecting unit for detecting a level variation of an optical signal and a level variation storing unit for storing information based on the level variation.

Abstract: A method for optical supervisory signaling includes determining a wavelength channel status (WCS) value, a wavelength channel failure (WCF) value, and a wavelength channel lit (WCL) value for each one of multiple data channels services by an optical communication node. The method further includes communicating the values to a second optical communication node.

Abstract: A receiver transponder to be used in an optical add and drop multiplexer connected in short haul type networks receives light signals from two opposite directions on input fibers (21, 23). The optical input signals are converted to electrical signals by O/E converters (51, 53). The output terminals of the converters are connected to an electronic switch (61) which handles protection switching in a protected ring type network. The output of the switch can be monitored (65) before, it enters a reshaping circuit (67) in which the signal is reshaped, cleansed from a supervisory channel and given a proper drive level for a following laser (69). The optical signal from the laser can travel a significant distance through a fiber (71) to a client receiver or sustain other forms of attenuation and still have a sufficient signal power for reliable detection. An electrical output signal can be provided (73) by the reshaping circuit.

Abstract: A packet transmission system is disclosed. The system serves between terminal apparatuses that include a supervisory control circuit configured to transmit a supervisory signal in a direction opposite to the transmission direction of a main signal on each of and both of an upstream circuit and a downstream circuit. The packet transmission system transmits overhead information of a packet frame of the main signal of the upstream circuit and the downstream circuit using the supervisory control circuit of the downstream circuit and the upstream circuit, respectively.

Abstract: An ring type optical LAN device includes a master node and a plurality of slave nodes that are interconnected by an optical fiber cable. A plurality of optical bypass transmission lines are provided in correspondence with each one of the slave nodes. Each of the optical bypass transmission lines bypasses the corresponding one of the slave nodes. Each slave node includes an E/O converter and an optical cutoff circuit. Each of the E/O converters is controlled to flash for generating an optical signal, which is transmitted to a network. When any one of the slave nodes fails such that the corresponding E/O converter is maintained in a turned on state, the associated optical cutoff circuit forcibly switches the E/O converter to a turned off state. This suppresses a network crash caused by the failure maintaining the E/O converter in the turned on state.

Abstract: A device (D) is dedicated to controlling the power of optical signals in a transparent switching node of an optical communication network that switches bands of wavelengths. The device includes, firstly, a controller (12) for comparing input optical power measurements to a selected first threshold and generating instructions representative of the comparison result, secondly, a measuring device (10A) for delivering measurements representative of the input optical power of the optical signals at one output at least of the switch (4), and thirdly, a processor between the switch (4) and the multiplexer (6) of the node and which control the optical power of the signals coming from the switch (4) as a function of the instructions they receive, so that the optical power of the signals at the input of the multiplexer (6) is maintained substantially constant.

Abstract: A repeater node for an optical transmission system provides amplification of optical signals and uses a modulated pump signal to transfer status information about the repeater node to a control system via an optical supervisory signal. The pump signal supplied by a pump source to an optical amplifier is modulated with one or more tones that are indicative of status in the repeater node. In a transmission fiber coupled to the output of the optical amplifier, the modulation of the pump signal is transferred to the supervisory signal of the optical transmission system as a result of Raman effect. More specifically, the pump wavelength and the supervisory signal wavelength are such that the modulated tone on the shorter wavelength pump signal is transferred to the longer wavelength supervisory signal. The tone can then be extracted from the supervisory signal and processed at another node in the system.

Abstract: A transmission system is provided that recognizes occurrence of a fault efficiently so that the workability and quality of service can be improved. An optical amplifier part amplifies an optical main signal. A fault occurrence recognizing part detects a pump light used for an opposing device via an optical fiber transmission line to which an optical main signal is sent by the repeater. If the pump light is not detected, the fault occurrence recognizing part recognizes occurrence of a fault. A light cutoff control part stops the optical amplifying part outputting an amplified signal so that the light cutoff control in only one of two directions is performed when a fault occurs.

Abstract: Method and apparatus for implementing optical supervisory channel using broadband noise modulation are described. One embodiment of the present invention is a system for transmitting a supervisory channel from an optical fiber amplifier. The system comprises a first stage amplifier and a noise modulator module. The noise modulator module includes an erbium-doped fiber (“EDF”) that receives a pump for exciting the EDF and emits an amplified noise signal and a modulator that modulates the amplified noise signal with a supervisory signal, wherein the modulated noise signal is input back into the first stage amplifier.

Abstract: An optical repeating system includes an optical transmitter and a plurality of optical amplifying repeaters. The optical transmitter specifies a part or all of the optical amplifying repeaters, and transmits a supervisory command to the specified optical amplifying repeaters as a first sub-signal via an uplink or downlink optical transmission line. The supervisory command is a command to supervise internal circuits of the optical amplifying repeaters. Receiving the supervisory command addressed thereto via the uplink or downlink optical transmission line, the optical amplifying repeaters each transmit a supervisory signal indicating a supervisory result corresponding to the supervisory command to optical receivers via the uplink and downlink optical transmission lines as a second sub-signal. The optical system can reduce the time take to acquire the supervisory information about the plurality of the optical amplifying repeaters.

Abstract: A repeater according to the present invention includes a plurality of excitation light sources with varying center wavelengths for use as an excitation light source to achieve Raman amplification; and comprises a flatness monitoring circuit which monitors the flatness of signal light on a transmission line; a monitor control circuit which controls externally said excitation light sources based on a remote supervisory control signal and which determines which of said excitation light sources to control as appropriate according to the flatness of signal light identified by said flatness monitoring circuit; and a bandwidth selective reflector or LD modules which, under the control of said monitor control circuit, outputs said flatness information to another repeater as a remote supervisory control signal with a specific wavelength, via said transmission line.

Abstract: This invention provides an improved graphical user interface (GUI) for optical network administration. The GUI allows a user to view a network topology in which only those nodes at which channel traffic may be added to and/or dropped from a muxed signal are displayed. The GUI also provides a view of optical components through which data is transmitted on a selected route, and a view of the individual channels which comprise the selected route. Finally, the GUI allows the user to view information relating to transmitters and receivers associated with the channel signals being transmitted along the selected route.

Abstract: A Raman amplifier repeater comprising a Raman excitation light production/answer signal superimposition unit for producing a first reply signal for a down-direction line with respect to a monitor control command, an answer signal production unit for producing a second reply signal with respect to the monitor control command, and a command reply switch for selectively using the first reply signal when an optical signal passing through a down-direction line on a second terminal station side is inputted as an answer signal with respect to the monitor control command and the second reply signal when the optical signal is not inputted through the second terminal station side down-direction line. With this configuration, high-quality monitor control is feasible even if a disconnection/break trouble occurs in an optical fiber in conducting the optical amplification repeating by the Raman amplification.

Abstract: A method and system for multi-level power management in an optical network is provided. They include three levels of power management. The first level of power management dynamically changes equipment settings in each module of equipment so that required module setpoint values in each module are achieved. The second level of power management determines module setpoint values for each module of equipment within each node in the optical link so that required node setpoint values are achieved. The third level of power management determines node setpoint values at each node in the optical link so that the optical link meets predetermined power specifications. If any of the three levels cannot achieve the required setpoint values, an error signal is generated by that level of power management and sent to the level of power management above it, thus initiating a higher level of power management.

Abstract: If a repeater supervisory control (SV), a pre-emphasis automatic adjustment (PE), a receiving side threshold value automatic adjustment (Vth), a transmitting side dispersion compensation value setting (VDC(T)), and a receiving side dispersion compensation value setting (VDC(R)) are executed for an optical main signal, these controls are executed in the above described priority order. Accordingly, if the controls are independently executed, or if two or more controls simultaneously occur, a control with a higher priority is executed. In this way, a transmission quality of an optical signal is prevented from being badly influenced as a result that the controls are simultaneously executed.

Abstract: An optical repeating system includes an optical transmitter and an optical amplifying repeater. The optical transmitter transmits a supervisory command and a control command to the optical amplifying repeater as a first sub-signal. The supervisory command is a command to supervise internal circuits of the optical amplifying repeater, and the control command is a command to control the optical amplifying repeater. The optical amplifying repeater includes multiple sub-modules each for amplifying and repeating main signals on multiple sets of optical transmission lines. When receiving the supervisory command via the optical transmission line, each sub-module transmits a supervisory signal indicating the supervisory result associated with the supervisory command to an optical receiver as a second sub-signal.

Abstract: An optical communication system includes a plurality of nodes coupled by an optical fiber. The optical fiber comprises a gain medium and is operable to transmit optical signals in a plurality of channels. An optical pump is coupled to the optical fiber, and is operable to generate and transmit an optical pump signal co-propagating with the optical signals. The optical pump signal comprises a specified walk-off with respect to the optical signals and is operable to Raman amplify the signals in the optical fiber while maintaining an eye penalty below 0.5 decibels.

Abstract: An optical transmission system capable of monitoring the operating status of Raman-amplifier repeaters even when an optical transmission line is partly disrupted by a fiber failure. An end station sends a monitoring command signal to request a particular repeater to report its operating status, together with a response carrier wave for use in that reporting. With their different wavelengths, an upstream wavelength selector in the repeater selectively passes the monitoring command signal while reflecting back the response carrier wave. Responsive to the command, a monitoring controller creates a response message containing operating status information. An excitation unit performs Raman amplification with a pump beam modulated by a modulation controller, so that the response message be superimposed on the response carrier wave propagating on the upstream link.

Abstract: The present invention provides an optical wavelength multiplexing transmission apparatus and an optical output control method for an optical wavelength multiplexing transmission apparatus in an optical wavelength multiplexing transmission system using a main signal light and an OSC light. The optical wavelength multiplexing transmission apparatus (10a) is made up of a first transmitting/receiving section (52a) a second transmitting/receiving section (52b) and an apparatus supervisory control unit (54). This can not only achieve quick restoration from troubles, but also stably calculate an optical output level even if a change of the number of wavelengths to be multiplexed takes place in a main signal light, and even save troublesome adjustments for the improvement of reliability of a transmission line while eliminating the need for a signal source for the adjustment of a receive optical level at the initial installation.

Abstract: A housing that includes separated and removable transmitter modules, and common receiver circuitry. The receiver is common to all modules, but the modules can be removed and replaced to allow different frequencies and the like. Each module also includes its own heat handling mechanism such as a heat sink.

Abstract: A repeater apparatus (1001) is constituted from infrared transmitter sections (1s, 2s, 3s) and infrared receiver sections (1r, 2r, 3r) as well as connection control sections (1C, 2C, 3C) and further a repeater section (101), thereby attaining independent communications with the individual one of several associated equipments with respect to infrared communication apparatus of the direct emission type which supports only one-to-one (1-to-1) or one-to-several (1-to-N) communication schemes, thus enabling achievement of N-to-N communication forms by performing transfer of data information being received by each communication equipment to others.

Abstract: A communication system that improves operation and maintenance and controls communication efficiently. A supervisory signal sending control section controls the sending of a supervisory signal for having supervisory control of optical communication and a drive supervisory signal for controlling the driving of an optical fiber amplifier for performing optical amplification by using a non-linear optical phenomenon in an optical fiber. A sending stop section receives a stop signal and stops the sending of the drive supervisory signal. A drive control section receives the drive supervisory signal and controls the driving of the optical fiber amplifier. A stop signal sending section sends the stop signal to a sending unit after the optical fiber amplifier being driven.

Abstract: An optical transmitter 11 outputs an optical signal, and an optical booster amplifier 12 amplifies the optical signal and sends the amplified optical signal to an optical fiber 101 forming an optical transmission line. When detecting an optical signal fluctuation factor, an optical transmitter control part 13 outputs a light surge warning signal 111 prior to an optical signal fluctuation, and a gain control part 14 responds to the light surge warning signal 111 to decrease the gain of the optical booster amplifier 12 down to a level where no light surge occurs.

Abstract: A method for determining gain for an optical signal includes measuring a first power level that is an output power level of an optical signal at a first optical node, communicating the optical signal to a second optical node, and communicating the first power level to the second optical node in an optical supervisory channel of the optical signal. The method further includes receiving the optical signal at the second optical node, measuring a second power level of the optical signal at the second optical node, and determining a gain for the optical signal based on the first and second power levels.

Abstract: A crosstalk compensation engine for reducing signal crosstalk effects within a data signal. Demultiplexed data signals corresponding to multiplexed data signals received via a signal transmission medium are processed to significantly reduce one or more signal crosstalk products related to one or more interactions among the multiplexed data signals within the signal transmission medium. Such signal crosstalk products include those resulting from dense wavelength-division mutiplexing of the data signals used to provide the multiplexed data signals, four-wave mixing among the multiplexed data signals within the signal transmission medium, and cross-phase modulation among the multiplexed data signals within the signal transmission medium.

Abstract: An optical transmission system ensuring high-quality monitor control even if an optical fiber fault occurs. A monitor instruction sending unit sends a monitor instruction. An operating condition recognizing unit receives a response signal and recognizes the operating condition. A filtering unit filters the monitor instruction and the response signal. A monitor control unit monitors the operating condition of its own repeater in response to the monitor instruction, and generates resultant response information. A pump unit generates a pump light to cause Raman amplification within an optical fiber transmission medium. A regeneration control unit performs a regeneration control of the response signal to thereby create a regenerated signal. A modulation control unit modulates the pump light by the response information or the regenerated signal to thereby generate the response signal.

Abstract: A unique sensor is used to detect a transmission impairment that may have affected incoming optical channel signals. The sensor, more specifically, selects a group of the incoming channel signals and generates a first power signal, P0, over the selected group of signals and generates a second power signals, P1, over a weighted version of the selected group of channel signals. The sensor then generates, as a function of the first and second power signals, P0 and P1, a signal indicative of whether the particular transmission impairment affected the levels of individual ones of the incoming channel signals. If so, then control apparatus offsets the impairment accordingly.

Abstract: The gain control circuit controls the amplification ratio of EDFA based on the results of having measured the input power monitor which monitors the EDFA input optical level which amplifies light and of having measured the output power monitor which monitors the output optical level. The optical pre-amplifier receives a notice of the number of wavelengths from a fore node and a notice of whether the optical post-amplifier of a fore node is in normal operation by a supervisory control signal, and changes over the gain control circuit to either the ALC or AGC mode. When the number of wavelengths changes while the optical pre-amplifier is operating in the ALC mode, the optical pre-amplifier is controlled in the AGC mode using the backed-up amplifier gain. Also, the gain value when the optical pre-amplifier is in routine operation is backed up in an amplifier gain back-up unit and an back-up unit.

Abstract: The present invention relates to an optical level control method for use in an optical transmission system. In the system, a WDM terminal comprises a multiplexing/demultiplexing unit, an amplifier, an up-direction OSC light transmitting/receiving unit, an up-direction multiplexer, an up-direction branching unit, an amplifier and an APR control unit, and a repeater comprises an up-direction branching unit, an OSC light transmitting/receiving unit, an amplifier, an up-direction multiplexer, a down-direction branching unit, an amplifier, a down-direction multiplexer and an APR control unit. In this configuration, a flexible optical output level control in connection with variation in WDM light level, a selective value irrespective of occurrence of an error stemming from the passage of time and avoidable malfunctions are respectively capable. In addition, a trouble retrieving operator can eliminate the possibility of being exposed to the WDM light.

Abstract: An apparatus for transferring monitor signals, which apparatus receives a primary signal, and a secondary signal for monitoring a wavelength, and outputs the primary signal and the modulated secondary signal. The apparatus includes an optical coupler to which the primary signal is input, a first optical branching filter optically connected to a signal output terminal, a first optical amplifier optically connected in series between the optical coupler and the first optical branching filter, and a first optical band-pass filter optically connected in series between the optical coupler and the first optical branching filter, but optically connected in parallel with the first optical amplifier. The primary signal is input into the optical coupler and output from the signal output terminal through the first optical amplifier and the first optical branching filter.

Abstract: The present invention provides an optical wavelength multiplexing transmission apparatus and an optical output control method for an optical wavelength multiplexing transmission apparatus in an optical wavelength multiplexing transmission system using a main signal light and an OSC light. The optical wavelength multiplexing transmission apparatus (10a) is made up of a first transmitting/receiving section (52a), a second transmitting/receiving section (52b) and an apparatus supervisory control unit (54). This can not only achieve quick restoration from troubles, but also stably calculate an optical output level even if a change of the number of wavelengths to be multiplexed takes place in a main signal light, and even save troublesome adjustments for the improvement of reliability of a transmission line while eliminating the need for a signal source for the adjustment of a receive optical level at the initial installation.

Abstract: A communication path impairment detection module for connection to a duplex optic communication link is provided. The duplex optic communication link includes an outgoing communication path and an incoming communication path, each being characterized by a data channel and an optical service channel. The communication path impairment detection module includes a first port and a second port suitable for coupling to the outgoing and incoming communication paths respectively. The communication path impairment detection module is responsive to impairment of the data channel and of the optical service channel in the incoming communication path to impair the data channel and the optical service channel in the outgoing communication path.

Abstract: A supervisory system and supervisory method of an optical amplifier repeater are proposed that can implement operation supervision taking account of the characteristics of individual supervisory targets of the optical amplifier repeater, thereby achieving higher reliability.

Abstract: The present invention has an object to obtain an optical signal quality supervisory device that supervises the quality of an optical signal simply, efficiently and with high accuracy without inviting an increase in cost, an increase in circuit scale and increase in power consumption. The bit rate of the optical supervisory channel is made lower than the bit rate of the optical main channel that is transmitted over an optical communication system, but the reception electric band width of a receiver that receives the optical supervisory channel is made equal to or wider than the reception electric band width of a receiver that receives the optical main channel. Also, the optical supervisory channel is made up of an SOH (section over head) frame to detect an error of the BIP (bit interleaved parity) byte of SOH, thereby supervising the quality of the optical communication system, in particular, the light wave network.

Abstract: A transmitter terminal in an ultra-long haul optical transmission system receives separate channel input signals in separate ones of a plurality of return-to-zero transmitters (RZTX). Each RZTX generates a corresponding forward error correction (FEC) modulated output signal in a separate channel frequency sub-band including predetermined channel separations from adjacent channel frequency bands. A multiplexing arrangement multiplexes the plurality of channel frequency bands from the RZTXs into separate groups of frequency bands. The groups of frequency bands have predetermined band-gap separations therebetween, and each group of frequency bands has a predetermined separate pre-chirp introduced therein before being multiplexed with all other groups of frequency bands into a single multiplexed output signal. An optical transmission line (OTL) is subdivided into predetermined sections and receives the single multiplexed output signal.