Patent application number | Description | Published |
20080226291 | OPTICAL RECEIVING APPARATUS AND OPTICAL LEVEL ADJUSTED QUANTITY SETTING METHOD THEREFOR - The present invention relates to an optical receiving apparatus designed to receive light wavelength-demultiplexed in a wavelength multiplex optical transmission system. The optical receiving apparatus includes an optical level adjusting unit for adjusting a level of light inputted and for outputting the level-adjusted light and a light receiving unit for receiving the light outputted from the optical level adjusting unit. An optical level adjusted quantity in the optical level adjusting unit is set so that the level of light of relatively shorter wavelength band becomes lower than the level of light of relatively longer wavelength band. This enables normal signal light reception to be achieved irrespective of a variation in the number of wavelengths with a simple configuration. | 09-18-2008 |
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 |
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 |
20080310011 | Optical Surge Suppressive Type Optical Amplifier - According to an optical surge suppressive type optical amplifier in the present invention, for a WDM optical amplifier having a multi-stages amplification configuration in which a plurality of optical amplifying means is connected in series, an optical amplifying medium capable of causing a homogeneous up-conversion (HUC) phenomenon is applied to the optical amplifying means on the signal light output side, so that an optical surge is suppressed utilizing the degradation of gain efficiency by the HUC caused at the time when the input power is decreased. Further, for a one wave optical amplifier, an optical amplifying medium capable of causing a pair induced quenching (PIQ) phenomenon is applied to the optical amplifying means on the signal light input side, so that the optical surge is suppressed utilizing the degradation of output power efficiency by the PIQ caused at the time when the input power is increased. As a result, it is possible to provide a low cost optical amplifier capable of effectively suppressing the optical surge without leading the complexity of control circuit or optical circuit configuration. | 12-18-2008 |
20090016727 | OPTICAL TRANSMISSION APPARATUS - An optical transmission apparatus includes a reception part for receiving a wavelength division multiplexed (WDM) signal reached via optical amplifiers; a measuring part for measuring an optical power level of each wavelength of the WDM signal received by the reception part; a determination part for determining whether an amount of tilt of the WDM signal calculated based on measurement results of the measuring part is suitable or not; an operation part for calculating the tilt correction amount to be applied to tilt correction processing performed by the optical amplifiers if the amount of tilt of the WDM signal is not suitable; and a notification part for notifying the optical amplifiers of the tilt correction amount. | 01-15-2009 |
20090169212 | Optical transmission apparatus and optical communication system - An optical communication system, where in an optical transmission apparatus arranged on a transmission side of respective repeating sections, an OSC optical amplifier is provided on an OSC light optical path between from an OSC transmitter to a multiplexer, and the OSC optical amplifier is controlled so that the power of OSC light transmitted on the transmission path becomes a previously set target value. As a result the OSC light is amplified by a different amplifying device to that for the main signal lights at the time of transmission. Therefore even in the case where the span losses are large, OSC light can be reliably received by the optical transmission apparatus on the reception side. | 07-02-2009 |
20090190204 | Wavelength division multiplexing optical transmission system utilizing distributed raman amplification - The WDM optical transmission system using distributed Raman amplification, before starting operation of main signal light, transfers a plurality of lights having different wavelengths to that of the main signal light (for example Raman amplification pump lights or the like) between first and second optical transmission devices connected to opposite ends of a transmission line, monitors transmission line input and output power for each light, calculates a transmission line loss in each wavelength using the monitor results, and specifies a type of the transmission line based on a loss wavelength characteristic that can be estimated from the calculation result. Then the power of pump light provided to the transmission light is optimized in accordance with the type of transmission line. | 07-30-2009 |
20090190205 | RAMAN AMPLIFYING DEVICE AND CONTROL METHOD - A light amplifying device including a Raman amplifier to Raman-amplify a signal light by inputting excitation lights of a plurality of wavelengths to a transmission path through which the signal light propagates, a plurality of measuring units measuring powers of light output from the Raman amplifier in a plurality of wavelength bands included in an amplification band of the Raman amplifier, a calculating unit calculating a ratio of the respective powers measured by at least two of the plurality of measuring units, and a control unit controlling a power ratio of the respective excitation lights input to the transmission path by the Raman amplifier based on the ratio calculated by the calculating unit. | 07-30-2009 |
20090190206 | RAMAN AMPLIFYING DEVICE AND CONTROL METHOD - A light amplifying device including a Raman amplifier to Raman-amplify a signal light by inputting excitation lights of a plurality of wavelengths to a transmission path through which the signal light propagates, a plurality of measuring units measuring powers of light output from the Raman amplifier in a plurality of wavelength bands included in an amplification band of the Raman amplifier, a calculating unit calculating a ratio of the respective powers measured by at least two of the plurality of measuring units, and a control unit controlling a power ratio of the respective excitation lights input to the transmission path by the Raman amplifier based on the ratio calculated by the calculating unit. | 07-30-2009 |
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 |
20090213454 | RAMAN AMPLIFICATION APPARATUS AND DISTRIBUTED RAMAN AMPLIFICATION SYSTEM AS WELL AS STARTING UP METHOD FOR DISTRIBUTED RAMAN AMPLIFICATION SYSTEM - A Raman amplification apparatus includes a pumping light supplying section, a main signal wavelength light level acquisition section, a monitoring signal wavelength light level acquisition section, a function information storage section for storing, as function information, information regarding functions for deriving a noise amount and a gain by Raman amplification with regard to a monitoring signal wavelength light with respect to pumping light power supplied from the pumping light supplying section, and a transmission characteristic derivation section for deriving a transmission characteristic on an optical transmission line based on information acquired by the main signal wavelength light level acquisition section and the monitoring signal wavelength light level acquisition section and the function information stored in the function information storage section, and Raman gain is derived with high accuracy in comparison with the conventional technique. | 08-27-2009 |
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 |
20090237778 | Monitoring method and apparatus of noise light due to raman amplification and optical communication system using the same - A monitoring apparatus, based on an optical power monitored in photodetectors arranged at input and output ends of a transmission line, in a condition where pump light is supplied to the transmission line at a time of initial startup of an optical communication system, obtains a relationship for the noise light generated due to Raman amplification, between forward direction noise light power and backward direction noise light power, and while in service, converts the backward direction noise light power monitored by the photodetectors at the input ends of the transmission line into the forward direction noise light power in an arithmetic processing section, in accordance with the relationship obtained at the time of the initial startup. As a result the power of noise light generated due to Raman amplification, can be monitored in real time at high speed. | 09-24-2009 |
20090238569 | OPTICAL TRANSMISSION APPARATUS AND OPTICAL COMMUNICATION SYSTEM - An optical transmission apparatus is provided with an optical filter on a transmission line between a reception end of a transmission line and an OSC receiver. The optical filter has transmission characteristics such as to pass main signal light and optical supervisory channel light (OSC light), and to cut off noise light contained in at least one end portion band on a short wavelength side and a long wavelength side of an OSC transmission band used for reception of OSC light. By such a configuration, even in a case where the OSC light is Raman amplified and transmitted, the influence of noise light due to Raman amplification can be reduced, and OSC light can be received reliably, enabling high dependability to be realized. | 09-24-2009 |
20100073762 | Raman amplifier and control method thereof - A Raman amplifier, at the time of start up or the like, drives a predetermined number of pump light sources among a plurality of pump light sources, in a stable region, and judges a Raman gain in the transmission line, and based on the judgment result, specifies a pump light source to switch on and a pump light source to switch off, among the plurality of pump light sources, and controls the drive state of the pump light sources that are switched on. As a result, the plurality of pump light sources are appropriately driven corresponding to the system requirements so that stable behavior is possible, and constant control of Raman gain can be realized at a high accuracy. | 03-25-2010 |
20100091357 | CONTROL APPARATUS OF OPTICAL AMPLIFIER - A control apparatus of an optical amplifier includes a monitoring section that measures power of light inputted to the optical amplifier, a power-wavelength characteristics variable section that is operable to change a wavelength characteristic of power of the light inputted, a wavelength number decrease recognition section that compares the value of the power of light measured by the monitoring section with a predetermined threshold, and a control section that controls the power-wavelength characteristics variable section when the wavelength number decrease recognition section judges that the value of the power of light falls below the threshold. | 04-15-2010 |
20100123949 | OPTICAL AMPLIFYING DEVICE - An optical amplifying device includes a first optical amplifier for amplifying signal light; a second optical amplifier serially connected with the first optical amplifier; an optical device for compensating deterioration of the signal light, the optical device arranged between the first optical amplifier and the second optical amplifier; a variable optical attenuator for attenuating the signal light, the variable optical attenuator arranged between the first optical amplifier and the second optical amplifier; a first automatic level controller for detecting a second amplifier output power and for controlling driving status of the second amplifier in a predetermined output power level; and a first automatic gain controller for detecting an input power of the second optical amplifier and an output power of the second optical amplifier, and for controlling an optical attenuation value of the variable optical attenuator. | 05-20-2010 |
20100129081 | DISTRIBUTED RAMAN AMPLIFIER AND OPTICAL COMMUNICATION SYSTEM - The distributed Raman amplifier monitors an OSNR of each channel in a WDM light which has been propagated through a transmission path to be Raman amplified, and thereafter, is amplified by an optical amplifier in an optical repeating node; judges whether a monitor value of the OSNR is larger or smaller than a previously set target value thereof; and feedback controls a driving state of a pumping light source which supplies a Raman pumping light to the transmission path, based on the judgment result. The optical communication system comprises the above distributed Raman amplifier in each repeating span thereof, and performs a pumping light control of the distributed Raman amplifier corresponding to the repeating span selected based on the OSNR in each distributed Raman amplifier and the monitor result of span loss. As a result, it becomes possible to effectively improve the OSNR of each channel in the WDM light, and also, to reduce the power consumption. | 05-27-2010 |
20100166425 | OPTICAL RECEIVER - An optical receiver for receiving a wavelength channel signal light separated out of a wavelength division multiplexed signal light including a plurality of wavelength channel signal lights, the optical receiver includes an optical amplifier for amplifying the wavelength channel signal light, a cyclic filter having a transmission wavelength characteristic of periodically changing transmittance property for a wavelength interval between a wavelength of an adjacent wavelength channel signal light and a wavelength of the wavelength diversion multiplexed signal light, the cyclic filter passing the wavelength channel signal light amplified by the optical amplifier, and a demodulator operably connected to the cyclic filter for demodulating the wavelength channel signal light output from the cyclic filter into an electrical signal. | 07-01-2010 |
20100221021 | OPTICAL RECEIVER AND CONTROL APPARATUS - An optical receiver that can receive WDM signal light in which first and second wavelength bands are combined. Within optical reception units corresponding to each channel is respectively provided tunable dispersion compensator (TDC) modules in which one wavelength band is made a design standard. When known, based on signal light channel information (wavelength, frequency, channel number) notified from outside, that signal light of the second wavelength band is being input to the receiver, then in the TDC module that performed chromatic dispersion compensation of the signal light, control is performed to shift the center frequency of the dispersion compensation range by a predetermined amount corresponding to the wavelength of the signal light. When the signal light of the first wavelength band is input, shift control of the dispersion compensation range is not performed, and the dispersion compensation range at the time of designing is maintained. As a result, chromatic dispersion compensation of signal light of respective wavelength bands can be performed with high accuracy by one type of TDC. | 09-02-2010 |
20100272391 | CHROMATIC DISPERSION COMPENSATOR - There is provided a chromatic dispersion compensator, which includes an optical circulator optically coupled to an input port and an output port, a chromatic dispersion compensation unit; including, and a light excitation source for supplying, to a light waveguide, excitation light. The chromatic dispersion compensation unit includes a light waveguide doped with the rare earth ion, a grating unit including a grating formed in at least a part of the longitudinal direction of the light waveguide, where the grating unit performing a chromatic dispersion compensation for a signal light input via the optical circulator to a one end of the light waveguide through the input port by reflecting the signal light flowing through the light waveguide according to a wavelength of the signal light and by returning the reflected signal light to the one end to lead to the output port via the optical circulator. | 10-28-2010 |
20100303459 | DISPERSION COMPENSATING APPARATUS, DISPERSION COMPENSATING METHOD, OPTICAL RECEIVING APPARATUS, AND OPTICAL RECEIVING METHOD - 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. | 12-02-2010 |
20100316392 | TUNABLE DISPERSION COMPENSATION APPARATUS, OPTICAL RECEPTION MODULE AND METHOD - An apparatus includes: a first dispersion compensator that is arranged on an optical path between an input port and an output port, that has a dispersion compensation band, and that substantially compensates a chromatic dispersion to signal light by using a variable amount of dispersion compensation, a second dispersion compensator that is arranged on the optical path, that has a dispersion compensation band different from the dispersion compensation band of the first dispersion compensator, and that substantially compensates the chromatic dispersion to the signal light by using a variable amount of dispersion compensation and a controller that controls the first dispersion compensator in accordance with the value of chromatic dispersion to be compensated and that controls the amount of dispersion compensation and the dispersion compensation band in the second dispersion compensator in association with the amount of dispersion compensation in the first dispersion compensator. | 12-16-2010 |
20110292500 | OPTICAL AMPLIFIER AND OPTICAL FIBER - An optical amplifier includes an optical fiber which includes a core in which the signal light is propagated and with which a rare-earth element is doped; a laser that is optically coupled to an end of the optical fiber, providing the optical fiber with an excitation light; and a filter which is formed in the optical fiber and removes a light within a wavelength range, from the core, among lights propagated in the core, wherein the filter comprises a first filter that is arranged at a stage of the optical fiber and removes a first light in a first wavelength range, and a second filter that is arranged at a subsequent stage of the optical fiber and removes a second light in a second wavelength range, wherein a wavelength of the second light is longer than a wavelength of the first light. | 12-01-2011 |
20120013975 | OPTICAL AMPLIFIER AND TRANSMISSION LOSS MEASUREMENT METHOD - An optical amplifier that amplifies signal light with Raman amplification in the Raman amplification medium. The optical amplifier includes a light source that supplies pump light into the Raman amplification medium, a first detector that detects input power of the pump light to be input to the Raman amplification medium, a second detector that detects output power of the pump light output from the Raman amplification medium, and a processor operable to calculate transmission loss of the pump light in the Raman amplification medium by comparing the input power with the output power, and calculate transmission loss of the signal light in the Raman amplification medium based on the transmission loss of pump light corrected based on a wavelength of the signal light and a wavelength of the pump light. | 01-19-2012 |
20120163810 | OPTICAL DEVICE, OPTICAL TRANSCEIVER UNIT, AND OPTICAL COMMUNICATION SYSTEM - An optical device includes an optical element that is secured to a base material, a temperature variable element the temperature of which is variable, the temperature variable element being secured to the base material such that light propagates between the temperature variable element and the optical element, a housing that houses the optical element and the temperature variable element, and a heat conducting medium that is disposed at a position that is different from a position of the base material and away from an optical path through which the light propagates, the heat conducting medium physically contacting the optical element and the temperature variable element. | 06-28-2012 |
20120293856 | OPTICAL DELAY DEVICE, OPTICAL CIRCUIT, AND OPTICAL DELAY METHOD - An optical delay device includes an optical path in which an input optical signal travels the same path recursively; an optical switch that switches between an output state of outputting the optical signal input to the optical path, and a non-output state of not outputting the optical signal input to the optical path; and a controller that sets the optical switch to the non-output state until a point in time when a given delay time elapses since input of the optical signal to the optical path and at the point in time when the given delay time elapses, switches the optical switch to the output state. | 11-22-2012 |
20140161453 | AMPLIFICATION APPARATUS AND COMMUNICATION SYSTEM - An amplification apparatus includes: a circulator to receive, at a first terminal, first signal light transmitted from OLT to ONU and first light having a predetermined wavelength different from the first signal light and, at a third terminal, second signal light transmitted from ONU to OLT and second light having the predetermined wavelength; a first reflector to output reflected light back to a second terminal; a first optical amplifier to have an amplification band characteristic of amplifying at least the first signal light; a second reflector to output reflected light back to a fourth terminal; a second optical amplifier to have an amplification band characteristic of amplifying the second signal light without amplifying the second light having the predetermined wavelength; and a first partial reflector to have a wavelength transmission characteristic of outputting the light having a wavelength different from the predetermined wavelength to the second optical amplifier. | 06-12-2014 |
20140270752 | OPTICAL TRANSMITTING DEVICE AND OPTICAL TRANSMISSION SYSTEM - An optical transmitting device includes: a laser diode to which a first or second driving current is provided; a controller to provide the laser diode with the first driving current to transmit an optical signal and with a plurality of second driving currents, to emit light, different from each other in magnitude during a stop of providing the first driving current; a measuring unit to measure an intensity of the light emitted by the laser diode; a calculator to calculate a threshold current of the laser diode, based on the intensities corresponding to the plurality of second driving currents measured by the measuring unit and magnitudes of the plurality of second driving currents; and a determination unit to determine a precursor of a sudden-death of the laser diode, based on an amount of variation in the threshold current calculated by the calculator during a specific period. | 09-18-2014 |
20140376083 | POLARIZATION REDUCING APPARATUS, LIGHT SOURCE APPARATUS, OPTICAL AMPLIFYING APPARATUS, AND EXCITATION LIGHT SOURCE APPARATUS FOR RAMAN AMPLIFICATION - A polarization reducing apparatus includes a separating unit configured to separate input light into components having polarization directions orthogonal to each other; a winding waveguide of silicon formed on a silicon substrate in a winding manner, the winding waveguide transmitting a first component among the components separated by the separating unit; an optical path configured to have a shorter optical path length than the winding waveguide, the optical path transmitting a second component among the components separated by the separating unit; a combining unit configured to combine the first component and the second component; and an output unit configured to output light consisting of the first component and the second component combined by the combining unit. | 12-25-2014 |