Abstract: A transmission apparatus includes: an assigning unit that assigns an information signal to a subcarrier with a frequency different from a frequency of a received radio signal; a creating unit that creates a multi-carrier signal, in which information signals are multiplexed, each of the information signals being assigned to one subcarrier by the assigning unit; and a multiplexing unit that frequency-multiplexes the received radio signal to the multi-carrier signal created by the creating unit and outputs a resulting frequency-multiplexed signal.

Abstract: An optical reception apparatus may include a receiver, a monitor, and a controller. The optical reception apparatus receives multi-carrier modulated signal light modulated by a multi-carrier modulation scheme. The multi-carrier modulation scheme is available to allocate different transmission conditions for each of a plurality of subcarriers in accordance with transmission characteristics of the subcarriers. The receiver may receive from an optical transmission line a training signal light allocated with the same transmission conditions for each of the subcarriers. The monitor may monitor the transmission characteristics of the training signal light to detect a frequency at which a dip of the transmission characteristics occurs. The controller may control, based on the frequency detected by the monitor, a dispersion compensation for the multi-carrier modulated signal light having received a dispersion from the optical transmission line.

Abstract: A multilevel-intensity modulation and demodulation system includes: a digital-to-analog conversion unit to convert an output level value of a digital signal into an analog signal; a multilevel-intensity-modulated light transmission unit to transmit an optical signal multilevel-intensity modulated based on the analog signal; a multilevel-intensity-modulated light reception unit to receive the optical signal multilevel-intensity modulated, and convert the received optical signal into an analog reception electrical signal; an analog-to-digital conversion unit to convert the analog reception electrical signal into a reception level value; and a controller to convert a transmission multiple gradation level being one of a plurality of multiple gradation levels of multilevel-intensity modulation to which the digital signal is mapped, into the output level value so as to cause the reception level value to be in a desired reception state, and to receive a digital signal corresponding to a reception multiple-gradation-

Abstract: A transmitting apparatus is used in an electrical frequency division multiplex transmission system including nodes that are on an optical transmission path and that respectively frequency-multiplex a sub-carrier of a unique frequency and a carrier wave to transmit information to a receiving apparatus on the optical transmission path. The transmitting apparatus is disposed in each node and includes a determining unit that receives an input of information concerning unused sub-carriers of a transmission signal in the optical transmission path and determines transmission of the information to the receiving apparatus using an unused sub-carrier; an electrical frequency division multiplex transmission unit that using a frequency of the unused sub-carrier determined by the determining unit, modulates the input information to be transmitted to the receiving apparatus; and a coupling unit that adds to the transmission signal in the optical transmission path, a modulated modulation signal.

Abstract: An optical transmission system includes: multiplex transmitting devices, each configured to modulate, with an optical carrier, a data signal modulated into light by an optical modulator in a non-linear optical medium arranged on a transmission path so as to multiplex the data signal into the optical carrier, the data signal having a frequency different in each of the multiplex transmitting devices; a receiving device configured to execute optical-to-electrical conversion on the optical carrier received from the transmission path so as to execute reception process of the data signals multiplexed by the multiplex transmitting devices; and a management device configured to specify a frequency band to be used, based on a modulation band of each of the optical modulators, and manage assignment of the frequency of each of the data signals within the frequency band to be used so as to avoid an effect of harmonics generated upon the optical-to-electrical conversion.

Abstract: An optical amplification apparatus includes a front-stage semiconductor optical amplifier which amplifies an input light and a rear-stage semiconductor optical amplifier which amplifies an amplified light outputted from the front-stage semiconductor optical amplifier. The front-stage semiconductor optical amplifier exercises auto level control of an output light by exercising variable control of driving current which flows according to applied voltage higher than light emitting threshold voltage of an internal optical amplification element. The rear-stage semiconductor optical amplifier performs gate switching of a transmitted light by exercising switching control of driving current. By doing so, distortion of a waveform is controlled and optical communication quality can be improved.

Abstract: A transmission apparatus includes: an assigning unit that assigns an information signal to a subcarrier with a frequency different from a frequency of a received radio signal; a creating unit that creates a multi-carrier signal, in which information signals are multiplexed, each of the information signals being assigned to one subcarrier by the assigning unit; and a multiplexing unit that frequency-multiplexes the received radio signal to the multi-carrier signal created by the creating unit and outputs a resulting frequency-multiplexed signal.

Abstract: A level control circuit that generates output signal for level control includes: a control information storage that stores control information corresponding to a signal level, a control information circuit that outputs the output signal for level control corresponding to the signal level of a first input signal based on the control information stored in the control information storage; and an information update circuit that updates the control information of the control information storage according to the signal level of a second input signal.

Abstract: A phase shift unit provides a prescribed phase difference (?/2, for example) between a pair of optical signals transmitted via a pair of arms constituting a data modulation unit. A low-frequency signal f0 is superimposed on one of the optical signals. A signal of which phase is shifted by ?/2 from the low-frequency signal f0 is superimposed on the other optical signal. A pair of the optical signals is coupled, and a part of which is converted into an electrical signal by a photodiode. 2f0 component contained in the electrical signal is extracted. Bias voltage provided to the phase shift unit is controlled by feedback control so that the 2f0 component becomes the minimum.

Abstract: An optical output level control apparatus includes a detector configured to detect power of an input optical signal; an amplifier configured to amplify the input optical signal; a memory configured to store data that define a first curved line representing a relationship between the input power and a drive voltage of the amplifier for obtaining a first output level and data that defines a second curved line representing a relationship between the input power and the drive voltage of the amplifier for obtaining a second output level; a generator configured to correct at least one of the first and second curved lines and generate a target curved line representing a relationship between input power and a drive voltage of the amplifier for obtaining a target output level through interpolation based on the first and second curved lines at least one of which is corrected.

Abstract: An optical communication network includes a plurality of optical transmission devices, a communication path, an optical repeater, and a supervisory controller that includes a supervisory control information sender which is installed on at least one of one of the optical transmission devices and the optical repeater and controls a drive signal supplied to a semiconductor optical amplifier that amplifies and outputs input signal light onto the communication path on the basis of the supervisory control information, and a supervisory control information receiver that receives the light which has been output from a semiconductor optical amplifier and transmitted through the communication path, converts the received light to an electric signal and identifies the supervisory control information on the basis of an intensity-modulated component of the total power of the electric signal in at least the other of one of the optical transmission devices and the optical repeater.

Abstract: A transmitting apparatus is used in an electrical frequency division multiplex transmission system including nodes that are on an optical transmission path and that respectively frequency-multiplex a sub-carrier of a unique frequency and a carrier wave to transmit information to a receiving apparatus on the optical transmission path. The transmitting apparatus is disposed in each node and includes a determining unit that receives an input of information concerning unused sub-carriers of a transmission signal in the optical transmission path and determines transmission of the information to the receiving apparatus using an unused sub-carrier; an electrical frequency division multiplex transmission unit that using a frequency of the unused sub-carrier determined by the determining unit, modulates the input information to be transmitted to the receiving apparatus; and a coupling unit that adds to the transmission signal in the optical transmission path, a modulated modulation signal.

Abstract: An optical output level control apparatus includes a detector configured to detect power of an input optical signal; an amplifier configured to amplify the input optical signal; a memory configured to store data that define a first curved line representing a relationship between the input power and a drive voltage of the amplifier for obtaining a first output level and data that defines a second curved line representing a relationship between the input power and the drive voltage of the amplifier for obtaining a second output level; a generator configured to correct at least one of the first and second curved lines and generate a target curved line representing a relationship between input power and a drive voltage of the amplifier for obtaining a target output level through interpolation based on the first and second curved lines at least one of which is corrected.

Abstract: An optical signal receiving apparatus includes: a chromatic dispersion medium having an amount of chromatic dispersion which is determined according to a frequency of the sub-carrier modulation signals so as to receive the sub-carrier modulation signals, a photodetector configured to convert the carrier optical signal that has passed through the chromatic dispersion medium, into electrical signals, and a signal receiving unit configured to receive an electrical signal selected from the electrical signals obtained by the photodetector.

Abstract: A waveform controller includes a monitor configured to monitor a waveform of an output pulse obtained by the response of a responsive element to a driving signal supplied thereto and a driving waveform shaper configured to shape a waveform of the driving signal based on a monitoring result obtained by the monitor.

Abstract: An optical transmission system includes: multiplex transmitting devices, each configured to modulate, with an optical carrier, a data signal modulated into light by an optical modulator in a non-linear optical medium arranged on a transmission path so as to multiplex the data signal into the optical carrier, the data signal having a frequency different in each of the multiplex transmitting devices; a receiving device configured to execute optical-to-electrical conversion on the optical carrier received from the transmission path so as to execute reception process of the data signals multiplexed by the multiplex transmitting devices; and a management device configured to specify a frequency band to be used, based on a modulation band of each of the optical modulators, and manage assignment of the frequency of each of the data signals within the frequency band to be used so as to avoid an effect of harmonics generated upon the optical-to-electrical conversion.

Abstract: In an optical access network system in which a relay station receives a wavelength multiplexed and time-division multiplexed optical signal (WDM optical signal) from an optical network, and the relay station transmits optical signals having specified wavelengths to subscriber units, the relay station demultiplexes the WDM optical signal into a plurality of groups with one group having a plurality of optical signals having a fixed wavelength interval between signals, then divides the optical signals of each group into k branches (k is the number of subscriber units) and inputs the signals to optical switches, and by turning ON/OFF the optical switches such that they are spaced in time, inputs the branched optical signals to the respective specified subscribers units.

Abstract: A relay apparatus including: a first interface 11 that branches an optical signal that is input in a first direction from one side of the optical transmission line, and directs the optical signal to a first path and a second path, the first path being a processing path of an optical signal having a first transmission speed, the second path being a processing path of an optical signal having a second transmission speed that is different from the first transmission speed; a processing section 12 that executes processing on an optical signal propagating through each of the paths in accordance with a corresponding transmission speed; and a second interface 13 that binds the first path and the second path of the optical signal on which the processing is executed by the processing section, by means of wavelength multiplexing and directs to the other end of the optical transmission line.

Abstract: In an optical access network system in which a relay station receives a wavelength multiplexed and time-division multiplexed optical signal (WDM optical signal) from an optical network, and the relay station transmits optical signals having specified wavelengths to subscriber units, the relay station demultiplexes the WDM optical signal into a plurality of groups with one group having a plurality of optical signals having a fixed wavelength interval between signals, then divides the optical signals of each group into k branches (k is the number of subscriber units) and inputs the signals to optical switches, and by turning ON/OFF the optical switches such that they are spaced in time, inputs the branched optical signals to the respective specified subscribers units.

Abstract: An apparatus has a plurality of transmitters for transmitting optical packet signals having wavelengths; a multiplexer for multiplexing the optical packet signals transmitted by the plurality of transmitters; a packet scheduler controlling a timing at which each of the transmitters transmits the optical packet signal; and an assister for controlling power of assist light in accordance with a signal from the packet scheduler and causing the assist light to be wavelength-multiplexed with the wavelength multiplexed light such that a total sum of power of the wavelength multiplexed light and the power of the assist light is held constant under a predetermined condition.