Abstract: A signal processing device processes reception signals of optical signals received by a receiver when the optical signals transmitted from a transmitter are propagated to the receiver via a plurality of paths, and includes: a signal-to-noise ratio calculating unit that calculates signal-to-noise ratios of the optical signals that have been propagated through the respective paths, from propagation distances of the optical signals in the respective paths, intensities of the optical signals transmitted from the transmitter, and intensities of noise with respect to the optical signals transmitted from the transmitter; an amplitude adjusting unit that adjusts amplitudes of the reception signals of the optical signals that have been propagated through the respective paths, using the corresponding signal-to-noise ratios calculated by the signal-to-noise ratio calculating unit; and a signal combining unit that combines the reception signals whose amplitudes have been adjusted by the amplitude adjusting unit.

Abstract: An object is to provide an optical transmission apparatus in which dummy lights can be arranged according to an arrangement of optical signals. A plurality of optical signals of different frequencies arranged in a frequency grid are input to a multiplexing unit and the multiplexing unit multiplexes the input optical signals. A dummy light output unit identifies a dummy light to be arranged in the frequency grid based on the plurality of optical signals and outputs the dummy light. A multiplexing unit multiplexes an optical signal multiplexed by the multiplexing unit and the dummy light output from the dummy light output unit to output a wavelength-multiplexed optical signal L.

Abstract: This disclosure describes C and L band optical communications module link extender, and related systems and methods. An example method may include receiving, by a dense wave division multiplexer (DWDM) at a headend, one or more optical data signals over only an L band. The example method may also include combining the one or more optical data signals. The example method may also include outputting the combined one or more optical data signals to a first WDM at the headend. The example method may also include outputting, by a first WDM, the one or more optical data signals to an amplifier at the headend. The example method may also include amplifying, by the amplifier, the one or more optical data signals. The example method may also include outputting the amplified one or more optical data signals to a coexistence filter. The example method may also include outputting, by the coexistence filter, the amplified one or more optical data signals to an optical switch.

Abstract: An optical amplifying device according to the present invention includes: an optical propagation path including an optical amplifier for amplifying input light; an excitation light source for generating excitation light to excite the optical amplifier; first and second optical receivers detect the power of the input light in the optical propagation path before being amplified by the optical amplifier and the power of the light in the optical propagation path after being amplified by the optical amplifier; a third optical receiver for detecting the power of light having a traveling direction opposite to that of the input light amplified by the optical amplifier, in the optical propagation path; and a control unit for controlling the excitation light source on the basis of the light power detected by the first optical receiver, the light power detected by the second optical receiver, and the light power detected by the third optical receiver.

Abstract: A fiber amplification system is provided for amplifying a laser pulse signal, e.g., an oscillator signal of an oscillator device. The fiber amplification system includes a fiber pre-amplification system having a short, fundamental-mode and step-index fiber configured to pre-amplify the laser pule signal to generate a seed signal and a main amplification system having a large core fiber configured to amplify the seed signal. The short, fundamental-mode step-index fiber can have a length no longer than about 30 cm, and a mode field diameter no less than about 30 ?m, e.g., in a range from 30 ?m to 60 ?m, as well as a high doping concentration needed to provide an absorption length no more than about 30 cm, for providing the seed signal for the large core fiber with low non-linearity.

Abstract: An information processing apparatus of a first information processing apparatus coupled to a second information processing apparatus via an optical fiber, the information processing apparatus includes a memory, and a processor coupled to the memory and the processor configured to store, into the memory, a first reception power of an optical signal received via the optical fiber when an initial value is stored in the memory, store, into the memory, a second reception power of the optical signal received via the optical fiber when the first reception power is stored in the memory, and stop receiving the optical signal when a difference between the first reception power and the second reception power is equal to or greater than a first threshold value.

Abstract: There are provided a communication device, a communication system, and a communication method. A communication device includes a first receiver configured to receive a data signal and generate a level control signal based on an initial level of the data signal and on an error rate of the data signal; and a transmitter configured to transmit the level control signal.

Abstract: An illumination source for igniting and sustaining a plasma in a plasma lamp of a laser-sustained plasma (LSP) broadband source includes one or more ignition lasers configured to ignite the plasma within a gas contained within the plasma lamp. The illumination sources also include one or more sustaining lasers configured to sustain the plasma. The illumination sources include a delivery optical fiber, one or more optical elements configured to selectively optically couple an output of the one or more ignition lasers, and an output of the one or more sustaining lasers to the delivery optical fiber.

Abstract: It is intended to suppress the deterioration of the transmission quality of an optical signal propagating through an optical fiber due to the intensity variation of a control signal. An exemplary aspect of the present invention includes outputting main signal light; generating a first optical signal by intensity-modulating an optical signal depending on a control signal; generating a second optical signal by intensity-modulating an optical signal depending on a differential component between a prescribed signal having a constant intensity and the control signal; outputting a wavelength-multiplexed optical signal by multiplexing the first optical signal being generated and the second optical signal being generated; and transmitting a transmitting signal by multiplexing the output main signal light being output and the wavelength-multiplexed optical signal being output.

Abstract: An optical amplifying apparatus and a method to control the same are disclosed. The apparatus includes a semiconductor device that integrates a variable optical attenuator (VOA) with a semiconductor optical amplifier (SOA). The VOA evaluates the optical power of an incident beam from a photocurrent generated therein. The attenuation of the VOA and the optical gain by the SOA are optionally determined based on the detected input power.

Abstract: A communication system includes a first optical system and a second optical system optically connected to a clamping laser and a pump laser. The first optical system includes first and second optical splitters. The first optical splitter is configured to receive a clamping laser signal from the clamping laser and split the signal into split clamping laser signals. The second optical splitter is configured to receive a pump laser signal from the pump laser and split signal into split pump laser signals. The second optical system is optically connected to the first optical system and includes amplifier systems. Each amplifier system is configured to receive a multiplexed signal. The second optical system includes first and second combiners optically connected to an erbium-doped fiber. The first combiner is optically connected to the first splitter, and the second combiner is optically connected to the second splitter.

Abstract: Embodiments of the present invention relate to the field of network communications and specifically discloses a method for monitoring optical performance of a wavelength channel, including: receiving, by a first node, an optical signal over an operating wavelength and obtaining, by the first node, optical performance of the unestablished wavelength channel by monitoring the optical signal at a receiving end. Embodiments of the present invention further disclose a system and a node device for monitoring optical performance of a wavelength channel.

Abstract: An optical transmission device includes a first power monitor to monitor a first signal into which second signals with respectively different wavelengths are multiplexed so as to measure received power of the first signal; an amplifier to amplify the first signal, to generate a third signal; a driver to drive the amplifier; a demultiplexer to separate the third signal into fourth signals with the different respectively wavelengths; second power monitors each to monitor each of the fourth signals so as to measure received power of each of the fourth signals; a memory to store therein data related to gain in the amplifier, the data corresponding to each of wavelengths of the second signals, with respect to parameters which are the received power measured by the first power monitor and driving condition; and a processor to calculate power of each of the second signals.

Abstract: To stabilize power to an optical multimode receiver a multimode variable optical attenuator is connected to the receiver with the attenuator's voltage being controlled using a feedback signal provided by an output detector, the signal being processed using a control algorithm based on proportional-integrate-differential theory.

Abstract: An optical amplifier includes: a first amplifier amplifying a signal light by a first excitation light; a variable optical attenuator attenuating the signal light; a second amplifier amplifying the signal light by a second excitation light; a mode selector selecting one of first and second modes; a gain controller, in first mode, controlling first and second excitation lights so that a gain of power of the signal light becomes constant; a first output controller, in second mode, controlling the first excitation light; a second output controller that, in second mode, controlling the second excitation light so that a spontaneous emission light having fixed level is outputted; and an attenuation controller controlling an attenuation of the variable optical attenuator according to an input level of the signal light in first mode, and controlling the attenuation to become a given value larger than a value of first mode in second mode.

Abstract: 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.

Abstract: A regenerative ring resonator in the path of a light beam includes a discharge chamber having electrodes and a gain medium between the electrodes; an optical coupler that is partially reflective so that at least a portion of a light beam impinging on the optical coupler from the discharge chamber is reflected back through the discharge chamber and at least a portion of the light beam impinging on the optical coupler from the discharge chamber is transmitted through the optical coupler; and an attenuation optical system in the path of the light beam within the resonator, the attenuation optical system having a plurality of distinct attenuation states, with each attenuation state defining a distinct attenuation factor applied to the light beam to provide adjustment of an energy of the light beam.

Abstract: A method and apparatus for suppression of four-wave mixing using polarization control with a high power polarization maintaining fiber amplifier system. The apparatus includes a master oscillator (MO) that generates a beam; a polarization controller that receives the beam from the MO and transmits the beam with a desired polarization; a pre-amplifier that receives the beam from the polarization controller, pre-amplifies the beam, and transmits the beam; a high power fiber amplifier that receives the beam from the pre-amplifier, amplifies the beam, and transmits an output beam; and a polarization detector that detects the polarization of the output beam. The polarization detector transmits feedback to the polarization controller to ensure that the output beam components aligned with the principal birefringent axes of the high power fiber amplifier have approximately equal power.

Abstract: An optical transmission node including an optical preamplifier to amplify input light and an optical postamplifier to amplify light output from the optical preamplifier, includes the optical postamplifier configured to generate amplified spontaneous emission light without signals input, the optical preamplifier configured to amplify the amplified spontaneous emission light from the optical postamplifier, a loopback switch configured to discouple a path of the light output from the optical preamplifier to the optical postamplifier, and couple a path of the light output from the optical postamplifier to the optical preamplifier.

Abstract: 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.

Abstract: 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.

Abstract: A generation unit generates a polarization multiplexing signal in which two optical signals, each polarization of which is orthogonal to each other, are combined. A detector detects the powers of the two optical signals contained in the polarization multiplexing signal generated by the generation unit. An amplifier amplifies, according to each polarization of the two optical signals contained in the polarization multiplexing signal generated by the generation unit, the powers of the two optical signals. An controller controls a gain of the amplifier with respect to each polarization of the two optical signals so as to reduce difference in the powers of the two optical signals detected by the detector.

Abstract: An optical network device of a passive optical network is introduced. The optical network device includes a light source, a control unit, and a variable optical attenuator. The light source can generate an optical signal. The control unit can generate a magnetic signal based on a control signal capable of providing information relating to a distance between the optical network device and an optical line termination. The variable optical attenuator can adjust a polarization angle of the optical signal based on the magnetic signal.

Abstract: A light output control apparatus, includes: an excitation light source that outputs excitation light; an excitation light guiding unit that guides the excitation light to an optical amplifying medium for transmitting a signal light; and a loss causing unit that includes an optical transmission medium located between the excitation light source and the excitation light guiding unit, and changes a radius of curvature of the optical transmission medium.

Abstract: An optically amplified wavelength division multiplexing network has the functionality to add/drop channels at the optical add/drop multiplexing (OADM) nodes. The OADM node includes a receiver amplifier, an OADM module, and a transmitter amplifier. Once the OADM node detects a loss of signal (LOS) due to a fiber cut or network element failure upstream, the receiver amplifier is kept in operation as a noise source. The output of the receiver amplifier is immediately raised by increasing pump power to compensate for the LOS. The noise power received at the transmitter amplifier from the receiver amplifier is substantially equal to the signal power expected before LOS. The transient effect of downstream optical amplifiers is therefore completely suppressed and the inter-channel stimulated Raman scattering (SRS) induced spectrum tilt does not change. After the noise power is raised, the receiver amplifier may be shut down at a speed much slower than the speed of downstream amplifier control circuitry.

Abstract: An apparatus and that provide an optical-fiber amplifier having at least one erbium-doped fiber section and an optical pump coupled to the erbium-doped fiber section, wherein the apparatus is operable to amplify signal pulses to high energy in the erbium-doped fiber section, the pulses having a wavelength in the range of about 1565 nm to about 1630 nm. In some embodiments, the amplifying fiber is ytterbium free.

Abstract: An optically amplified wavelength division multiplexing network has the functionality to add/drop channels at the optical add/drop multiplexing (OADM) nodes. The OADM node includes a receiver amplifier, an OADM module, and a transmitter amplifier. Once the OADM node detects a loss of signal (LOS) due to a fiber cut or network element failure upstream, the receiver amplifier is kept in operation as a noise source. The output of the receiver amplifier is immediately raised by increasing pump power to compensate for the LOS. The noise power received at the transmitter amplifier from the receiver amplifier is substantially equal to the signal power expected before LOS. The transient effect of downstream optical amplifiers is therefore completely suppressed and the inter-channel stimulated Raman scattering (SRS) induced spectrum tilt does not change. After the noise power is raised, the receiver amplifier may be shut down at a speed much slower than the speed of downstream amplifier control circuitry.

Abstract: 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.

Abstract: A fiber optical audio preamplifier receives audio signals from an audio source, amplifies the audio signals, and transfers the signals to a power amplifier. The fiber optical audio preamplifier has at least one first signal converter. Each first signal converter acquires one audio signal from one audio source and converts the audio signal to a modulated light signal. At least one fiber optic volume control device that includes a variable optical attenuator that is connected to receive the modulated light signal. A control signal for sets an attenuation factor of the variable optical attenuator for attenuating the modulated light signal to control volume of the audio signal. One second signal converter is in communication with each fiber optic volume control device to receive the attenuated modulated light signal and demodulate the attenuated modulated light signal to recover the audio signal for transmission to the power amplifier.

Abstract: An optically amplified wavelength division multiplexing network has the functionality to add/drop channels at the optical add/drop multiplexing (OADM) nodes. The OADM node includes a receiver amplifier, an OADM module, and a transmitter amplifier. Once the OADM node detects a loss of signal (LOS) due to a fiber cut or network element failure upstream, the receiver amplifier is kept in operation as a noise source. The output of the receiver amplifier is immediately raised by increasing pump power to compensate for the LOS. The noise power received at the transmitter amplifier from the receiver amplifier is substantially equal to the signal power expected before LOS. The transient effect of downstream optical amplifiers is therefore completely suppressed and the inter-channel stimulated Raman scattering (SRS) induced spectrum tilt does not change. After the noise power is raised, the receiver amplifier may be shut down at a speed much slower than the speed of downstream amplifier control circuitry.

Abstract: A method for amplifying a time-varying optical signal comprising the steps of: generating an auxiliary optical signal the amplitude of which is chosen to be complementary to at least the envelope of the amplitude of the optical signal, superimposing the auxiliary optical signal to the optical signal resulting in a compound signal having an amplitude which is constant at least on average, amplifying the compound signal, and removing the amplified auxiliary optical signal from the amplified compound signal; as well as an optical amplification unit for carrying out the method.

Abstract: A method of operating an amplifier system includes providing a pump signal at a pump wavelength. The pump signal is a function of a pump power. The method also includes providing an input signal at a signal wavelength and coupling the pump signal and the input signal to an optical amplifier. The optical amplifier includes a gain medium characterized by a gain value at the signal wavelength. The method further includes amplifying the input signal to provide an output signal, detecting a feedback signal related to the gain value, and modifying the pump power based on the detected feedback signal.

Abstract: An optical amplifier including an input port and an output port which are coupled together via a data signal line; an amplifier circuit; a gain control circuit coupled to the data signal line and operative for detecting the power level of a burst signal input into the optical amplifier at the input port; and a dummy laser generation circuit having an output coupled to the data signal line and an input coupled to the gain control circuit; where the gain control circuit is operative for controlling the power level output by the dummy laser generation circuit so as to maintain the power level of a signal input into the amplifier circuit at a substantially constant level.

Abstract: An optical transmitting apparatus includes a variable optical attenuating unit for attenuating signal light variably, an optical amplifying unit for amplifying the signal light, and a looped optical circuit for returning the signal light from the optical amplifying unit to the variable optical attenuating unit. The variable optical attenuating unit further attenuates the returned signal light variably.

Abstract: The present invention provides an optical amplifier pre-emphasis and equalization method that alleviates the optical amplifier gain ripple penalty experienced in conventional optical communications systems. This method includes storing measured communications channel signal gain ripple information, acquired during factory calibration, in the internal memory of each optical amplifier module. When the optical amplifiers are assembled into a chain, system software retrieves this communications channel signal gain ripple information from each optical amplifier module and computes the pre-emphasis or equalization required for each channel in order to obtain a flat SNR at a receiver. The method also includes measuring the ambient temperature of each optical amplifier module and applying a correction based on the expected change in gain response of each optical amplifier. The method further includes, for Raman amplifiers and the like, applying a fiber type, gain setting, GFF error, etc.

Abstract: An optical amplifying device disposed on a transmission path of a WDM signal includes an optical amplifier amplifying the WDM signal, a detecting unit detecting a change in a transmission wavelength count contained in the WDM signal and/or a change in light receiving level of the optical amplifier, a measuring unit measuring an optical signal to noise (SN) ratio of the WDM signal outputted from the optical amplifier, an update unit updating a reference value for evaluating the measurement value of the optical SN ratio obtained by the measuring unit when the detecting unit detects the change, a judging unit judging whether or not the measurement value deviates from an allowable range based on a reference value, and an output unit outputting an error of the optical amplifier if the measurement value deviates from the allowable range.

Abstract: An optical amplifying apparatus connected mutually through an optical transmission line includes an optical detecting unit for detecting an input level of an amplified spontaneous emission (ASE) light, an optical amplifying unit for amplifying a signal light, and an optical attenuating unit for adjusting an attenuation level for the signal light, which being installed on an input side of the optical amplifying unit. The optical attenuating unit adjusts the attenuation level for the signal light, based on a difference between an output level of the ASE light outputted from the preceding optical amplifying apparatus and the input level of the ASE light inputted thereto.

Abstract: A contrivance, if a WDM signal state changes, is to improve an optical transmission quality by compensating gain flatness. A first excitation control unit sets a first optical pumping light source unit to emit excitation power needed to get the same amplifying operating level of a first amplifying medium as at the time of a maximum wavelength count when allocating wavelengths after a change in wavelength count at an equal interval in a wavelength range. A wavelength allocation bias estimation unit compares a present monitor value of optical power after outputting of a gain equalizer 13 with wavelength equi-allocation power associated with the recognized wavelength count, and thus estimates a wavelength allocation bias occurred as a concomitant of the change in the wavelength count. A primary gradient calculation unit obtains a primary gradient quantity defines as a gain deviation from the wavelength allocation bias.

Abstract: An optical amplifier includes an output unit that outputs a loss monitoring light having a wavelength that causes neither absorption nor gain with respect to each of the wavelengths of a light signal to be amplified with EDFs; a multiplexing unit that multiplexes the loss monitoring light with the light signal at an input stage of the light signal; a demultiplexing unit that demultiplexes the loss monitoring light from multiplexed light signal at an output stage of the light signal; a detecting unit that detects intensity of loss monitoring light at the input stage and intensity of loss monitoring light at the output stage; a calculating unit that calculates, based on the intensities, a loss of the loss monitoring light that has occurred between the input stage and the output stage; and a control unit that controls, based on the loss, the variable optical attenuator.

Abstract: The invention discloses an optical amplifier (18) that amplifies signal light in a signal band in a fiber optic transmission system (10) having at least first and second optically pumped signal light gain amplifying stages (30), a tilt controller (40) linked to a control unit, a optical monitor (34) analyzing signal powers, characterized in that the amplified spontaneous emission of the optical amplifier (18) is measured at two extreme wavelengths of the signal band to derive control signals (44) for at least the tilt controller (40).

Abstract: An optical communication system includes a plurality of optical channels, each of which passes a single optical wavelength signal. Each of the plurality of optical channels includes an optical amplifier which is controlled to operate at a predetermined output power level independent of channel wavelength and input power level by operating each optical amplifier in a saturation mode. Pumping power for operating each optical amplifier in the saturation mode is supplied from shared optical pumps or a plurality of one per channel optical pumps.

Abstract: A request method for performing optical power management to accomplish planned addition and removal of wavelengths in an optical communications system is disclosed, wherein each wavelength has a path of transmission through the system. The method comprises communicating a request for a power ramp to at least one path network component in the path, determining that the path network component has made preparations for the power ramp, and performing a power ramp in response to the determination. Further, a response method for performing power management to accomplish planned addition and removal of wavelengths in an optical communications system is disclosed, wherein each wavelength has a path of transmission through the system. The method comprises receiving a request for a power ramp, making preparations for the power ramp, determining that the power ramp has been completed, and resuming normal operation in response to the determination.

Abstract: An optical amplifier capable of holding the gain profile of the optical amplifier constant includcs a rare-earth doped optical waveguide serving as an amplification medium, a pump light source for exciting the amplification medium, one or more control light source, a monitor, and a control unit. A control method is also provided for using the amplifier for holding the gain profile of the optical amplifier constant by, for example, controlling the control light source so that the calculated gain is matched with a prescribed value or an externally decided value.

Abstract: The optical amplifier apparatus comprises an optical amplifier which amplifies an input signal light, an output detecting unit which detects an output level of the optical amplifier, an output control unit which controls an output level of the optical amplifier according to an output level detected by the output detecting unit, a gain inclination detecting unit which detects a gain inclination relating to a wavelength of the optical amplifier, and a gain inclination control unit which controls a gain inclination of the optical amplifier according to a gain inclination detected by the gain inclination detecting unit.

Abstract: An optical pulse testing apparatus incorporating an optical pulse generator composed of low cost components. The optical pulse testing apparatus comprises: a ring optical path including an optical fiber 30 with a rare earth element added to; an excitation light source 32 which enters excitation optical pulses into the optical fiber 30; an optical branching filter 38 for branching the circulating optical pulses circulating through the ring optical path to emit output optical pulses; and a photodetector 40 for detecting the circulating optical pulses circulating through the ring optical path to obtain signals indicative of a light intensity and a generation timing of the circulating optical pulses. Thus, the optical pulse generator, and the optical pulse testing apparatus and method using the optical pulse generator require no expensive optical parts and complicated device control.

Abstract: Optical transmission systems of the present invention include at least one optical amplifier generally including an optical signal amplifying medium supplied with pump power in the form of optical energy in via an optical pump source. The pump source includes multiple optical sources, at least two of which provide optical energy in first and second wavelength ranges separated by a frequency difference. The amplifier includes a wavelength controller configured to adjust the wavelength range of at least one of the optical sources to vary the frequency difference in a manner sufficient to vary optical intensity noise produced when the optical energy from the multiple optical sources is combined.

Abstract: Disclosed is a wavelength-division multiplexing optical transmission system in which an optical lossy medium, optical amplifiers and Raman amplifiers for compensating for loss in the optical lossy medium are cascade-connected. The system includes power-level equalizing means for equalizing optical power levels input to an optical amplifier of a succeeding stage by adjusting excitation ratio of a Raman amplifier; optical-SNR equalizing means for adjusting power levels at a transmitting end to equalize optical SNRs at a receiving end; and correction-value acquisition means for acquiring a correction value that represents an amount of change in power of each wavelength before and after optical-SNR equalization control.

Abstract: The method according to the present invention includes the steps of splitting an optical signal into first and second optical signals, increasing the pulse widths of the first optical signal to obtain waveform shaped light, generating clock pulses according to the second optical signal, and inputting the waveform shaped light and the clock pulses into an optical AND circuit 10 to obtain a converted optical signal. According to the present invention, it is possible to suppress amplitude noise or the like generated in the optical AND circuit due to the jitter or temporal instability of the optical signal and the clock pulses.

Abstract: A performance monitoring method for an optically amplified transmission system. The method provides the optical power at each amplifier site, taking into account the inaccuracies introduced by the SRS in the power estimation obtained with the current methods. An optical spectrum analyzer is used at the output of the transmission link of interest to accurately measure the output power of each wavelength. This value is sent upstream to the last amplifier in the link, to compute an error term as the difference between the actual measurement and the estimation. The error term is used to infer the SRS-induced error by system elements not accounted for in the model. The error term is then fed-back to each amplifier in the link, so that the estimated power is adjusted to account for the SRS-induced inaccuracy.

Abstract: A programmable amplifier 100 operable to independently adjust the amplification given to various optical signals passing through an optical fiber. An input optical fiber 102 provides a number of optical signals to a demultiplexer which separates each signal carried by the input fiber 102. Each individual wavelength travels to a variable attenuator 106 which lowers the signal strength of each signal based on an input from the system controller 108. The attenuated signals are combined by multiplexer 112 and input to an optical amplifier 114. The optical amplifier 114 receives the combined signal and amplifies each signal in the combined DWDM signal across the entire bandwidth of the amplifier 114. The amplified signals are input to a splitter 116 which removes a small portion of the entire spectrum output by the amplifier 114. The remaining portion of the signal passes to an output fiber 110 and travels to the remainder of the optical network.