Patent application number | Description | Published |
20080199182 | Transmission system and transmission method - A wavelength division multiplexing system according to the present art adjusts the amount of dispersion compensation (the amount of dispersion compensation of an NZ-DSF and a DCF) every all spans on the basis of the time slot when an intensity modulation signal transmitter outputs an intensity modulation signal and the wavelength interval when a wavelength coupler multiplexes a phase modulation signal (output from a phase modulation signal transmitter) and the intensity modulation signal. | 08-21-2008 |
20080239469 | GAIN CONTROL APPARATUS, OPTICAL TRANSMISSION APPARATUS, GAIN CONTROL METHOD FOR OPTICAL AMPLIFIER, AND WAVELENGTH MULTIPLEX OPTICAL TRANSMISSION SYSTEM - The present invention relates to an apparatus for controlling a gain of an optical amplifier, and the apparatus comprises a target gain calculating unit for calculating, as a target gain for an optical amplifier, a value obtained by increasing or decreasing a gain (output) of signal light as the number of wavelengths of wavelength-multiplexed signal light decreases, and a control signal outputting unit for outputting a control signal to the optical amplifier so as to amplify the wavelength-multiplexed signal light with the target gain calculated by the target gain calculating unit. This promptly suppresses a fluctuation of signal light level, particularly, a fluctuation of output light power of an optical amplifier stemming from a variation of the number of wavelengths of wavelength-multiplexed signal light. | 10-02-2008 |
20090041456 | Wavelength division multiplex signal monitoring system and wavelength division multiplex transmission device equipped with the same - A WDM signal monitoring system includes a measuring unit that measures power levels in a plurality of predetermined wavelength bands about a wavelength division multiplex signal, a waveform determination unit that determines an approximate waveform of each channel from each bit rate and modulation system of a plurality of channels which forms a wavelength division multiplex signal, and an approximation unit that determines a power level and a wavelength of each channel by approximating the power level in a plurality of wavelength bands which the measuring unit measured with the approximate waveform of each channel which the waveform determination unit determined. | 02-12-2009 |
20090195862 | DISTRIBUTED RAMAN AMPLIFYING SYSTEM, START-UP METHOD THEREOF, AND OPTICAL DEVICE - To obtain automatic gain control with high accuracy by including first and second light monitors, a reference light supplying unit supplying reference light of which wavelength is set within a gain band of a distributed Raman amplification and out of a wavelength band of main signal light to the optical transmission path, a first reference light monitor monitoring a power of the reference light input to the optical transmission path from one end side thereof, a second reference light monitor monitoring the power of the reference light output from the other end side of the optical transmission path, and a controlling unit controlling supply of pump light in a pump light supplying unit as well as supervising a state of the optical transmission path, based on monitor results from the first and second light monitor and the monitor results in the first and second reference light monitors. | 08-06-2009 |
20090195863 | Optical amplification apparatus, optical communication apparatus, and optical communication method - A Raman amplifier inputs pump light into an optical fiber (transmission path) through which an optical signal passes, to amplify the optical signal. An optical receiving unit is provided downstream of the Raman amplifier and monitors the power of the optical signal amplified by the Raman amplifier. A calculating unit determines Raman amplification gain based on the power of the optical signal monitored by the optical receiving unit, and calculates the power of a noise component included in the optical signal based on the gain. The calculating unit, in real-time, calculates the power, which varies in complicated manners depending on conditions, and outputs information concerning to the power to another apparatus at a frequency on the order of milliseconds. | 08-06-2009 |
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 |
20090226167 | METHOD OF UPGRADING OPTICAL NODE, AND AN OPTICAL NODE APPARATUS - An optical node apparatus according to the present invention amplifies a WDM signal light input to an input port, and thereafter, branches the amplified WDM signal light by an optical branching coupler to send the branched lights to first and second optical paths, and selects the light propagated through the first optical path by an optical switch to amplify the selected light by a post-amplifier, thereby outputting the amplified light from an output port, when the optical node apparatus is operated as an optical amplification repeating node. When the operational state is upgraded to an optical add/drop multiplexing node, an OADM section is connected between a set of connecting ports on the second optical path, and the adjustment of the OADM section is performed utilizing the WDM signal light branched by the optical branching coupler, and thereafter, the switching of the optical switch is performed to select the light on the second optical path side. As a result, since the switching the operational state from the optical amplification repeating node to the OADM node can be performed in a short time, it becomes possible to provide the continued communication service at the low initial installation cost. | 09-10-2009 |
20100067917 | OPTICAL TRANSMISSION APPARATUS, OPTICAL TRANSMISSION METHOD, AND OPTICAL TRANSCEIVER - An aspect of the embodiments utilizes an optical transmission apparatus which includes a rough adjustment execution portion that monitors a bit error rate of an optical signal for set values of a dispersion compensator where the set values have been set less closely to each other within a dispersion compensation control range than when a wavelength dispersion value set in the dispersion compensator is determined, and carries out a rough adjustment to determine a comparison threshold value used to set the wavelength dispersion value based on the monitored bit error rate, and a fine adjustment execution portion that monitors the bit error rate for the dispersion compensator the set values have been set more closely to each other, and carries out an adjustment to determine a wavelength dispersion value corresponding to the midpoint between the two acquired bit error rates as the wavelength dispersion value of the dispersion compensator. | 03-18-2010 |
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 |
20120002270 | OPTICAL TRANSMISSION SYSTEM - An optical transmission system includes an optical transmitter that sends signal light to a transmission path, an optical receiver that receives the signal light from the transmission path, and an optical amplifier that is provided on the transmission path and that amplifies the signal light, the optical amplifier being configured to control a gain characteristic of the optical amplifier such that a power of signal light having a wavelength included within a wavelength range in which polarization hole burning occurs is higher than a power of another signal light having a wavelength outside the wavelength range. | 01-05-2012 |
20120063771 | WDM OPTICAL TRANSMISSION SYSTEM AND CONTROL METHOD THEREOF - A WDM optical transmission system includes a plurality of optical nodes optically coupled by a transmission line, a processor that is operative to calculate an amount of adjustment of a reception level capable of increasing an optical signal-to-noise ratio for each channel of the WDM light reaching the optical node positioned at a receiving end of the unit section based on information on amplification operation of the WDM light in at least one optical-amplification repeating node disposed on the optical transmission line in the unit section, and to adjust a power level corresponding to each channel of the WDM light transmitted on the transmission line from the optical node positioned at a transmission end of the unit section in accordance with a calculation result of the calculation. | 03-15-2012 |
20120106971 | OPTICAL TRANSMISSION DEVICE AND OPTICAL TRANSMISSION SYSTEM - An optical transmission device includes: an optical signal generator to generate and transmit an optical signal that transmits data; a detector to detect a number of active clients; and a processor to determine transmission rate of the optical signal according to the number of active clients and quality of the optical signal at an optical receiver. | 05-03-2012 |
20130045007 | MULTI-WAVELENGTH LIGHT AMPLIFIER - A multi-wavelength light amplifier includes a first-stage light amplifier which has a first light amplifying optical fiber amplifying a light input, a second stage light amplifier which has a second light amplifying optical fiber amplifying a first light output from the first-stage light amplifier, and an optical system which maintains a second light output of the second-stage light amplifier at a constant power level. The first-stage and second-stage light amplifiers have different gain vs wavelength characteristics so that the multi-wavelength light amplifier has no wavelength-dependence of a gain thereof. | 02-21-2013 |
20130251367 | CONTROL METHOD, OPTICAL TRANSMISSION DEVICE, AND CONTROL DEVICE FOR OPTICAL TRANSMISSION SYSTEM, AND OPTICAL TRANSMISSION SYSTEM - An optical transmission device includes: a controller that controllably extends a pass band of an optical transmission path for transmission of a known symbol sequence; and a transmission processing unit that provides the known symbol sequence after the controller controllably extends the pass band. | 09-26-2013 |
20140043675 | CONTROLLER WHICH CONTROLS A VARIABLE OPTICAL ATTENUATOR TO CONTROL THE POWER LEVEL OF A WAVELENGTH-MULTIPLEXED OPTICAL SIGNAL WHEN THE NUMBER OF CHANNELS ARE VARIED - An optical amplifier which amplifies a wavelength division multiplexed optical signal having a variable number of channels associated with different wavelengths and outputs the amplified WDM optical signal. The optical amplifier includes a first optical amplifier which amplifies the wavelength division multiplexed optical signal and outputs the first optical amplifier amplified wavelength division multiplexed optical signal; a variable optical attenuator which controls a level of the first optical amplifier amplified wavelength division multiplexed optical signal and outputs the controlled wavelength division multiplexed optical signal; a second optical amplifier which amplifies the controlled wavelength division multiplexed optical signal and outputs the amplified, controlled wavelength division multiplexed optical signal; and a controller which controls the wavelength division multiplexed optical signal to be amplified with a constant gain. | 02-13-2014 |