Patent application number | Description | Published |
20080239470 | INDIVIDUAL BAND GAIN EQUALIZER FOR OPTICAL AMPLIFIERS - A control apparatus comprises a light monitoring unit for dividing a signal wavelength band into at least a band in which output light power of an optical amplifier tends to decrease at an decrease in the number of signal wavelengths and a band including a gain deviation band, and for monitoring inputted light power for the individual divided bands, a calculation unit for obtaining the number of signal wavelengths in the individual divided bands based on a monitor result, and a target gain correction unit for correcting a target gain based on a result of the calculation. This suppresses a transient variation of signal light level due to SHB or SRS at a high speed with a simple configuration without deteriorating noise characteristic, thus enabling optical amplifiers to be further disposed in a multi-stage fashion, which can lengthen the transmission distance of a transmission system including an optical add/drop unit. | 10-02-2008 |
20090041473 | Optical device, optical modulation method, and optical transmitter - An optical modulation device including waveform shapers that waveform-shape input data signals in synchronism with a rising or falling timing based on comparison with a reference level of an input clock signal, a multi-level phase modulator that generates a multi-level-phase-modulated optical signal based on the data signals waveform-shaped by the plurality of waveform shapers, and outputs the generated optical signal, and a level ratio controller that varies a relative level ratio of the reference level to an amplitude level of the clock signal input to the waveform shapers, based on the optical signal output from the multi-level phase modulator. | 02-12-2009 |
20090219609 | Optical amplifier provided with control function of pumping light, and optical transmission system using the same - In an optical transmission system according to one aspect of the present invention, for transmitting a WDM light from a transmission station to a reception station, utilizing a Raman amplifier, the Raman amplifier comprises: an optical amplification medium; a pumping light source generating a plurality of pumping lights having wavelengths different from each other; an optical device introducing the plurality of pumping lights to the optical amplification medium; and control means for controlling the pumping light source, the transmission station sends out a plurality of reference lights having wavelengths at which respective Raman gain obtained by the plurality of pumping lights reach peaks or wavelengths close to the above wavelengths, and the control means controls the plurality of pumping lights based on the optical powers of the plurality of reference lights. Thus, it becomes possible to accurately manage the optical power balance of the WDM light and the optical power of the entire WDM light. | 09-03-2009 |
20100054756 | Optical modulator and optical transmitter using the same - In an optical modulator, a DQPSK modulating section, a waveguide optical amplifying section, and an RZ modulating section are cascade connected on an optical path between input and output ports, and power of RZ-DQPSK signal light output from the output port is monitored by a photodetector, to feed-back control the waveguide optical amplifying section by an output control section so that the monitored power becomes constant at a target level. As a result, a small and low-cost optical modulator that can reliably compensate respective losses in a phase modulating section and an intensity modulating section, and differences of the respective losses, can be realized. | 03-04-2010 |
20100157416 | Optical amplifier provided with control function of pumping light, and optical transmission system using the same - In an optical transmission system according to one aspect of the present invention, for transmitting a WDM light from a transmission station to a reception station, utilizing a Raman amplifier, the Raman amplifier comprises: an optical amplification medium; a pumping light source generating a plurality of pumping lights having wavelengths different from each other; an optical device introducing the plurality of pumping lights to the optical amplification medium; and control means for controlling the pumping light source, the transmission station sends out a plurality of reference lights having wavelengths at which respective Raman gain obtained by the plurality of pumping lights reach peaks or wavelengths close to the above wavelengths, and the control means controls the plurality of pumping lights based on the optical powers of the plurality of reference lights. Thus, it becomes possible to accurately manage the optical power balance of the WDM light and the optical power of the entire WDM light. | 06-24-2010 |
20100178065 | DELAY PROCESSING APPARATUS, SIGNAL AMPLIFICATION APPARATUS, OPTO-ELECTRIC CONVERSION APPARATUS, ANALOG-DIGITAL CONVERSION APPARATUS, RECEIVING APPARATUS, AND RECEIVING METHOD - A delay device that provides a delay amount to at least one of the in-phase signal and the quadrature signal, and a delay control section that controls the delay amount provided by the delay device based on a quality of the signals when the in-phase signal and the quadrature signal, to the at least one of which the delay amount is provided, at the delay device are converted into digital signals by the analog-digital converter, and the digital signal processing is carried out at the processor are provided. Thereby, the signal quality of recovered data at a receiving end of a multi-level phase modulation communication system is improved. | 07-15-2010 |
20110222853 | POLARIZED-WAVE-MULTIPLEXING OPTICAL TRANSMITTER AND CONTROL METHOD OF POLARIZED-WAVE-MULTIPLEXED OPTICAL SIGNAL - A polarized-wave-multiplexing optical transmitter including: an optical combiner generating a polarized-wave-multiplexed optical signal by polarized-wave-multiplexing a first optical modulation signal and a second optical modulation signal; an optical power fluctuation portion fluctuating optical power of the first optical modulation signal and the second optical modulation signal periodically; a total-optical-power detection portion detecting fluctuation amount of total optical power of the polarized-wave-multiplexed optical signal; and an optical power controller reducing an optical power difference between the first optical modulation signal and the second optical modulation signal based on detection result of the total-optical-power detection portion. | 09-15-2011 |
20110229148 | OPTICAL MODULATION APPARATUS AND OPTICAL MODULATION METHOD - An optical modulation apparatus includes a first modulator, a second modulator, a multiplexer, a detector and an adjustor. The first modulator modulates light emitted by a light source using a first input signal and outputs a first modulated signal. The second modulator modulates the light using a second input signal and outputs a second modulated signal. The multiplexer multiplexes the first and second modulated signals and outputs a multiplexed signal. The detector is configured to detect a dip where power in a waveform of the multiplexed signal is equal to or smaller than a predetermined value. The adjustor is configured to adjust a delay of the first and second input signals based on power at the dip. | 09-22-2011 |
20110229150 | OPTICAL MODULATION APPARATUS AND OPTICAL MODULATION METHOD - An optical modulation apparatus includes a first modulator, a second modulator, a multiplexer, a calculator and an adjustor. The first modulator configured to modulate light emitted by a light source using a first input signal and output a first modulated signal. The second modulator configured to modulate the light using a second input signal and output a second modulated signal. The multiplexer configured to multiplex the first and second modulated signals and output a multiplexed signal. The calculator configured to calculate a power difference between a higher-side frequency component having a frequency higher than a center frequency of the multiplexed signal and a lower-side frequency component having a frequency lower than the center frequency. The adjustor configured to adjust delays of the first and second input signals based on the power. | 09-22-2011 |
20120148235 | CONTROL CIRCUIT, COMMUNICATION SYSTEM, AND CONTROL METHOD - A communication system includes a transmitter, a receiver device, and a control circuit. The transmitter transmits an optical signal. The receiver device receives the optical signal. The control circuit reduces a power consumption of the receiver device based on an accumulated chromatic dispersion of the received optical signal. The receiver device includes a receiver, an analog/digital converter, and a digital signal processor. The receiver extracts a signal indicating a complex amplitude of the optical signal. The analog/digital converter converts the signal indicating the complex amplitude into a digital signal. The digital signal processor digitally-processes the digital signal. | 06-14-2012 |
20120237212 | OPTICAL NETWORK SYSTEM - There is provided an optical network system in which optical signals modulated by each of at least two modulation methods are wavelength-division-multiplexed and transferred, including: an optical transmitter configured to transmit first optical signals modulated by each of at least two modulation methods; an add-drop multiplexer configured to drop second optical signals from wavelength-division-multiplexed optical signals transferred in the optical network system, and add the first optical signals to the wavelength-division-multiplexed optical signals; an optical receiver configured to demodulate the second optical signals corresponding to each of at least two modulation methods; and a controller configured to control wavelengths of the first optical signals, the second optical signals and the wavelength-division-multiplexed optical signals so as to rearrange wavelengths of the first optical signals, the second optical signals and the wavelength-division-multiplexed optical signals so that optical signals modulated by a same modulation method are placed on an adjacent wavelength. | 09-20-2012 |
20120263456 | SKEW SUPPRESSION METHOD AND OPTICAL TRANSMISSION SYSTEM - A method for suppressing a skew between a first channel and a second channel in an optical transmission system having a transmitter that transmits an optical signal with the first channel and the second channel and a receiver that receives the optical signal, the method includes: controlling dispersion added to the optical signal to be larger than a specified amount; and controlling a delay time of at least one of the first channel and the second channel in the receiver based on a quality of the optical signal monitored in the receiver to suppress the skew between the first channel and the second channel in the receiver. | 10-18-2012 |
20130063809 | OPTICAL AMPLIFIER AND MULTICORE FIBER - An optical amplifier includes a pump light source that outputs pump light, and a multicore fiber that includes at least one pumping core, the pump light being input to the at least one pumping core by coupler, at least two signal light cores doped with an active substance for optical amplification, at least one signal light being input to at least one of the signal light cores, and a cladding, wherein the pump light propagating the at least one pumping core and exciting the active substance in the signal light cores, so as to amplify the at least one signal light propagating through the at least one of the signal light cores. | 03-14-2013 |
20130121693 | OPTICAL TRANSMISSION SYSTEM, PUMP-LIGHT SUPPLY CONTROL METHOD, AND PUMP LIGHT SUPPLY APPARATUS - An optical transmission system for communicating between transmission devices includes a first pump light source that supplies a first pump light, a second pump light source that supplies a second pump light, an optical transmission line that propagates an optical signal between the transmission devices, and a plurality of couplers that form a plurality of zones in the transmission line, the first pump light source and the second pump light source being optically connected to different couplers of the plurality of couplers, the second pump light Raman-amplifying the first pump light in a zone in which the second pump light is input in the transmission line. | 05-16-2013 |
20130302031 | OPTICAL TRANSMITTER AND OPTICAL SIGNAL TRANSMISSION METHOD - An optical transmitter includes: an optical modulator configured to generate an optical signal from a plurality of transmission signals; a crosstalk monitor configured to monitor crosstalk between the plurality of transmission signals by using the optical signal; and a crosstalk canceller configured to correct the plurality of transmission signals based on a result of monitoring by the crosstalk monitor. | 11-14-2013 |
20140099111 | PON SYSTEM AND SUBCARRIER ASSIGNING METHOD - A PON (Passive Optical Network) system, which modulates multiple subcarriers with data of multiple users to output an optical multiplexed signal from a station device, splits the optical multiplexed signal to transmit the split signals to multiple subscriber devices that are provided for each of the users, and demodulates the data of the users at the respective subscriber devices, includes: an obtaining section configured to obtain a transmission characteristic for each of the subcarriers at each of the subscriber devices, by receiving a test signal at the subscriber devices, which is transmitted from the station device; and an assigning section configured to assign one or more of the subcarriers for each of the subscriber devices suited to the transmission characteristics of the assigned subcarriers at each of the subscriber devices. | 04-10-2014 |
20140099114 | OPTICAL SIGNAL TRANSMITTING APPARATUS, OPTICAL FREQUENCY DIVISION MULTIPLEX TRANSMISSION SYSTEM, AND OPTICAL SIGNAL COMMUNICATION METHOD - An optical signal transmitting apparatus is disposed in an optical frequency division multiplex transmission system that includes plural nodes that are in an optical transmission path and respectively use a unique frequency to frequency-multiplex information with a carrier wave to transmit the information to an optical signal receiving apparatus in the optical transmission path. The optical signal transmitting apparatus outputs the carrier wave and includes a transmitting unit into which information to be delivered to the nodes is input, the transmitting unit transmitting the information using a frequency that does not overlap the unique frequencies used by the nodes; and a multiplexing unit that frequency-multiplexes output of the transmitting unit and the carrier wave, and sends the frequency-multiplexed output to the optical transmission path. | 04-10-2014 |
20140099115 | TRANSMITTING APPARATUS, RECEIVING APPARATUS, OPTICAL FREQUENCY DIVISION MULTIPLEX TRANSMISSION SYSTEM, AND OPTICAL SIGNAL COMMUNICATION METHOD - 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. | 04-10-2014 |
20140153925 | TRANSMISSION CONTROL DEVICE, TRANSMISSION SYSTEM, AND TRANSMISSION METHOD - A transmission control device includes a subcarrier selector configured to select one or more subcarriers for transmitting an error correction code for correcting data, from a plurality of subcarriers having different transmission capacities, each of the plurality of subcarriers used for transmitting either of the data and the error correction code, in accordance with an amount of data of the error correction code and transmission capacities respectively assigned to the plurality of subcarriers. | 06-05-2014 |
20140369677 | OPTICAL TRANSMITTER AND OPTICAL TRANSMISSION METHOD - An optical transmitter converts a plurality of transmission signals transmitted via a plurality of lanes into a multi-carrier signal and transmits the multi-carrier signal. The optical transmitter includes: a controller configured to generate allocation information that indicates an allocation of sub-carriers to the plurality of lanes according to a bit rate of the transmission signal of each of the lanes and a possible transmission capacity of each of the sub-carriers; and a signal processor configured to convert the plurality of transmission signals into the multi-carrier signal in accordance with the allocation information generated by the controller. | 12-18-2014 |
20150071642 | OPTICAL TRANSMITTER, OPTICAL RECEIVER, OPTICAL TRANSMISSION SYSTEM, OPTICAL TRANSMITTING METHOD, OPTICAL RECEIVING METHOD AND OPTICAL TRANSMISSION METHOD - An optical transmitter includes: a digital signal process unit that generates a drive signal for generating multi-carrier signals through a plurality of independent digital signal processes, the multi-carrier signals having a cyclic prefix and to be transmitted by a parallel transmission; a synchronization unit that synchronizes clocks of the plurality of digital signal processes; and an adjust unit that reduces a delay difference of the cyclic prefix between the multi-carrier signals after the parallel transmission. | 03-12-2015 |