Abstract: An optical amplifier module includes a first optical amplifier to amplify main signal light to be supplied to a dispersion compensation fiber (DCF), a second optical amplifier to amplify the main signal light supplied from the DCF, a generating part to generate monitoring light having a wavelength longer than a wavelength of the main signal light, a multiplexing part to multiplex the monitoring light generated by the generating part and the main signal light to be supplied to the DCF, a demultiplexing part to demultiplex the monitoring light from the main signal light supplied from the DCF, and a detection part to detect a light intensity of the monitoring light demultiplexed by the demultiplexing part.

Abstract: A wavelength dispersion measurement method includes generating a plurality of test lights in the first terminal, the wavelengths of which are different from a wavelength of a signal light, multiplexing each test light with the signal light and outputting the multiplexed light to the first transmission path, reconverting each electrical signal after converting each beam into electrical signals, multiplexing each test light with the signal light and outputting the multiplexed light to the second transmission path, reconverting each electrical signal after converting each test light into electrical signals, multiplexing each test light with the signal light and outputting the multiplexed light to the first transmission path, measuring times for each test light to be propagated up to a specified number of go-around, and measuring a change of a wavelength dispersion amount in the paths based on a difference between the measured propagation times of each wavelength.

Abstract: A tunable dispersion compensation device includes a plurality of tunable dispersion compensators coupled in series, a controller configured to control an amount of chromatic dispersion to be set in each of the plurality of tunable dispersion compensators, and a table including a correspondence relationship between an amount of chromatic dispersion and a wavelength band, for each of the plurality of tunable dispersion compensators, wherein the controller decides an amount of chromatic dispersion to be set in each of the plurality of tunable dispersion compensators, based on a total amount of chromatic dispersion desired for the plurality of tunable dispersion compensators and the correspondence relationship included in the table so that a difference between bandwidths of a first tunable dispersion compensator having the widest wavelength band and a second tunable dispersion compensator having the narrowest wavelength band, among the plurality of tunable dispersion compensators, is within a given range.

Abstract: A dispersion compensation device includes: an optical branching unit to branch an optical signal to be received; a first dispersion compensator to perform dispersion compensation on one part of the optical signal branched by the optical branching unit with a variable compensation amount; a second dispersion compensator to perform dispersion compensation on another part of the optical signal branched by the optical branching unit; a monitoring unit to monitor the communication quality of an output optical signal of the second dispersion compensator; and a controlling unit to determine the direction of variation in chromatic dispersion of the optical signal based on the direction of variation in communication quality monitored by the monitoring unit and control the compensation amount of the first dispersion compensator based on the result of the determination.

Abstract: An optical amplifier apparatus includes an optical amplifier including an amplification medium doped with an active substance, the amplification medium excited in order to amplify light; a semiconductor optical amplifier arranged after the optical amplifier; a driver for supplying a driving current with respect to the semiconductor optical amplifier in order that the semiconductor optical amplifier has an amplification characteristic with respect to an input light, the amplification characteristic including a gain non-saturated region and a gain saturated region; and an input-light level adjuster for adjusting an out put light of the optical amplifier to the input light level of the semiconductor optical amplifier, the input light level being set up between the gain non-saturated region and the gain saturated region.

Abstract: Equipped between a transmitter 20 and an optical multiplexer module 25 of a division/multiplexer unit 24 are band-pass filters 23-1 through 23-m letting only a light of right wavelength pass while reflecting other wavelengths light. The transmitter 20 is equipped with a reflection light monitor 26 for monitoring a reflection light from the band-pass filters 23-1 through 23-m for examining an intensity of a reflection light. A wavelength of a light oscillated by a tunable laser diode (LD) unit 21 is controlled so as to make the intensity of the light smaller than a threshold value.

Abstract: An optical transmission device includes an extractor that extracts respective optical signals from optical signals multiplexed from a plurality of optical signals of different wavelengths, a detector that detects wavelengths of the extracted respective optical signals, a storage that stores the wavelengths of the detected respective optical signals, and a processor that is operative to derive trends in wavelength variation of the respective optical signals based on the detected respective optical signals and the respective optical signals stored in the storage, and determines that either one or both of the extractor and the detector cause the wavelengths to be varied when the trends in wavelength variation of two or more wavelengths are the same.

Abstract: In a transmission apparatus, a monitor unit monitors a signal level and generates a monitored value; a level control unit controls the level of the input signal in accordance with the monitored value; an output amplification unit amplifies and outputs the level-controlled signal; and a control unit controls unit operation statuses in accordance with setting information. The control unit recognizes the period of duration of a single level in the input signal, from the signal format given by the setting information, and performs variable control of at least one of a monitor time constant, a response time from the signal input to the monitor unit until the generation of the monitored value, and a level setting time constant, a response time from the input of the monitored value to the level control unit until the execution of level control, in accordance with the period of duration of the single level.

Abstract: A wavelength dispersion measurement method includes generating a plurality of test lights in the first terminal, the wavelengths of which are different from a wavelength of a signal light, multiplexing each test light with the signal light and outputting the multiplexed light to the first transmission path, reconverting each electrical signal after converting each beam into electrical signals, multiplexing each test light with the signal light and outputting the multiplexed light to the second transmission path, reconverting each electrical signal after converting each test light into electrical signals, multiplexing each test light with the signal light and outputting the multiplexed light to the first transmission path, measuring times for each test light to be propagated up to a specified number of go-around, and measuring a change of a wavelength dispersion amount in the paths based on a difference between the measured propagation times of each wavelength.

Abstract: A signal-light detection apparatus includes a polarization extractor that extracts a polarization component that is substantially in parallel with a specified axial direction from an input light, a polarization rotator that changes a relative angle between a direction of polarization of the input light and an axial direction of the polarization extractor, a photodetector that detects an optical power of the polarization component extracted by the polarization extractor, and a determination device that determines whether the input light includes a signal component, based on a variation in the optical power detected by the photodetector.

Abstract: A dispersion compensation device includes: an optical branching unit to branch an optical signal to be received; a first dispersion compensator to perform dispersion compensation on one part of the optical signal branched by the optical branching unit with a variable compensation amount; a second dispersion compensator to perform dispersion compensation on another part of the optical signal branched by the optical branching unit; a monitoring unit to monitor the communication quality of an output optical signal of the second dispersion compensator; and a controlling unit to determine the direction of variation in chromatic dispersion of the optical signal based on the direction of variation in communication quality monitored by the monitoring unit and control the compensation amount of the first dispersion compensator based on the result of the determination.

Abstract: A controller monitors output level variation rate of excitation light outputted by a light source in accordance with a drive current of the light source and provided to a rare-earth doped amplifying medium so that a signal light is amplified as the signal light travels through the amplifying medium. In an embodiment, the controller decreases the drive current when the monitored output level variation rate is larger than a threshold value, to thereby reduce power level of the outputted excitation light and thereby delay progress of degradation of the light source indicated by the monitored output level variation rate being larger than the threshold value.

Abstract: An optical transmission device includes: a variable dispersion compensator to give chromatic dispersion and output an input light, a branching unit to branch the light output from the variable dispersion compensator to a first part and a second part, a reproduction unit to reproduce an electric signal from the first part of the input light, a monitor unit to perform reproducing processing on the electric signal from the second part of the input light, control the variable dispersion compensator based on a result of the reproducing processing, and has a sensitivity to a variation of the chromatic dispersion which is higher than the sensitivity to the variation of the chromatic dispersion of the reproduction unit.

Abstract: There is provided an optical transmission receiver includes an optical switch configured to switch between optical transmission channels, the optical transmission channels being gradually switched from one to the other, an optical amplifier configured to amplify a light propagating in the other of the optical transmission channels which is in a state subsequent to switching, and a switching speed controller configured to control a switching speed of the optical switch based on a level of the light amplified by the optical amplifier.

Abstract: A dispersion compensating apparatus includes a tunable dispersion compensator that dispersion-compensates an optical signal using a group delay property that is asymmetrical in bands outside an effective band; a set device that sets a dispersion compensation amount in the tunable dispersion compensator; and a shifter that shifts a central frequency of the effective band of the tunable dispersion compensator, based on the dispersion compensation amount set by the set device.

Abstract: An optical amplifier module includes a first optical amplifier to amplify main signal light to be supplied to a dispersion compensation fiber (DCF), a second optical amplifier to amplify the main signal light supplied from the DCF, a generating part to generate monitoring light having a wavelength longer than a wavelength of the main signal light, a multiplexing part to multiplex the monitoring light generated by the generating part and the main signal light to be supplied to the DCF, a demultiplexing part to demultiplex the monitoring light from the main signal light supplied from the DCF, and a detection part to detect a light intensity of the monitoring light demultiplexed by the demultiplexing part.

Abstract: A chromatic dispersion compensation control method for compensating the chromatic dispersion of an optical transmission path with a variable dispersion compensator inserted in the optical transmission path is disclosed.

Abstract: In a transmission apparatus, a monitor unit monitors a signal level and generates a monitored value; a level control unit controls the level of the input signal in accordance with the monitored value; an output amplification unit amplifies and outputs the level-controlled signal; and a control unit controls unit operation statuses in accordance with setting information. The control unit recognizes the period of duration of a single level in the input signal, from the signal format given by the setting information, and performs variable control of at least one of a monitor time constant, a response time from the signal input to the monitor unit until the generation of the monitored value, and a level setting time constant, a response time from the input of the monitored value to the level control unit until the execution of level control, in accordance with the period of duration of the single level.

Abstract: An optical transmitting station changes a power level of control signal light having a first frequency at a second frequency lower than the first frequency, and transmits the control signal light whose power level has been changed to an optical receiving station through an optical transmission line. The optical receiving station monitors whether signal light components of the second frequency are received through the optical transmission line.

Abstract: An optical amplifier apparatus includes an optical amplifier including an amplification medium doped with an active substance, the amplification medium excited in order to amplify light; a semiconductor optical amplifier arranged after the optical amplifier; a driver for supplying a driving current with respect to the semiconductor optical amplifier in order that the semiconductor optical amplifier has an amplification characteristic with respect to an input light, the amplification characteristic including a gain non-saturated region and a gain saturated region; and an input-light level adjuster for adjusting an out put light of the optical amplifier to the input light level of the semiconductor optical amplifier, the input light level being set up between the gain non-saturated region and the gain saturated region.