Abstract: A laser beam multiplexer capable of easily multiplexing a plurality of laser beams is provided. A laser beam multiplexer includes a multiplexing element having a hollow portion with a sectional elliptical shape, in which the multiplexing element includes: a plurality of light-incident apertures guiding laser beams from outside toward one of two focal points of the hollow portion, a reflective layer arranged on a wall surface of the hollow portion, and multiplexing a plurality of incident laser beams while reflecting the plurality of laser beams, and a light-emitting aperture guiding laser beams multiplexed by the reflective layer toward outside.

Abstract: The present invention provides a system and method for monitoring and providing settings to nodes in a telecommunications fiber network. The method and system reviews alarm and threshold settings of nodes and in the network. If the alarm and threshold settings a node are not within set standards, the standard alarm and threshold settings may be provided to the nodes. The method and system of the invention also calculates span loss between nodes in a telecommunications fiber network and the amplification levels of nodes in the network.

Abstract: Disclosed is a short-distance communication method and an apparatus using visible light. The apparatus scans ambient light, measures optical power of visible light, among visible light included in the ambient light, having a wavelength corresponding to a transmission wavelength used for the visible light communication, compares a minimum transmission optical power of transmitted light, a real transmission optical power, and the measured optical power of the ambient light, selects a transmission wavelength of the transmitted light on which noises caused by the ambient light have little effect, and performs the visible light communication using the visible light of the selected transmission wavelength.

Abstract: Provided is a method of reducing power consumption of an optical access network (OAN) as much as possible by configuring an optical line terminal (OLT) and optical network terminals (ONTs) in the OAN to support a maximum power-saving mode. According to the method, upon the application of power, an ONT operates normally in an activation mode. The ONT then determines whether the requirements for switching from activation mode to power-saving mode are satisfied. If the requirements are satisfied, the ONT transmits a sleep signal to an OLT, which is a message notifying that the ONT will soon switch to power-saving mode. Thereafter, the ONT switches to power-saving mode and cuts off power for all functions except for power for monitoring and controlling external inputs. The ONT then determines whether the requirements for switching from power-saving mode to activation mode are satisfied.

Abstract: A diagnostic and prescriptive system and method for management of a combined optical and RF cable plant system. In an exemplary embodiment the method and system uses optical receivers in a hub or headend to determine a variety of cable plant parameters such as the OMI of the received signal and automatically facilitated prescriptive service through prioritization and automatic recalibration. In another exemplary embodiment the method allows doing such signal OMI measurements in a closed loop system (that is a fully operational system). In addition, a further exemplary method and system allows storing of standard receiver calibration information such that from thereon signal OMI measurements that can be performed without signal interruption.

Abstract: A communication device includes an enclosure including a recess member including a bottom wall and an accommodating portion, a circuit board mounted on the bottom wall, and a light guiding member received in the accommodating portion. The circuit board includes a plurality of light sources arranged in a circular array. The light guiding member includes a light guiding portion to transmit light from the light sources to an outer surface of the communication device and a light shielding portion to shield the light to the outer surface and fix the light guiding portion in the accommodating portion. The light guiding portion includes a light guiding bottom wall surrounding the light sources and a light guiding sidewall. The light guiding sidewall includes an annular end surface to indicate signal strength and a strong signal orientation received by an antenna of the communication device.

Abstract: The invention relates to a method and a device for operating an optical transmitting device having a plurality of optical transmitters that can be driven independently. The method includes detecting the parameter values of the individual transmitters, comparing the parameter values determined with one another and/or with a prescribed comparison value, and selecting one of the transmitters for the communication operation of the transmitting device based on the comparison. The method further includes operating the transmitting device with the selected transmitter.

Abstract: An optical signal processing device for shaping a waveform of an optical signal, including: an intensity inversion wavelength converter configured to generate an intensity-modulated optical signal of a second wavelength obtained by inverting a signal intensity of an input intensity-modulated optical signal of a first wavelength; an optical coupler configured to multiplex the intensity-modulated optical signal of the first wavelength and the intensity-modulated optical signal of the second wavelength at a timing at which signal intensities of those signals become opposite; and an optical limiter configured to input coupled light output from the optical coupler, and suppress gain as power of the coupled light becomes higher.

Abstract: A method for measuring an optical power includes: acquiring code type information in an optical signal of a communication system, in which the optical signal includes an optical signal of burst emission and/or an optical signal of burst reception; measuring the optical signal of the communication system, and acquiring an optical power value of the optical signal; and correcting the optical power value according to the code type information.

Abstract: In an optical transmitter comprising a directly modulated laser and a wavelength filter provided on a post-stage of the directly modulated laser, the wavelength filter has a modulated light input port for inputting modulated light output from the directly modulated laser, a filter transmitted light output port for outputting light having a wavelength included in a filter transmission band among the modulated light as filter transmitted light, and a filter cutoff light output port provided separately from the modulated light input port and the filter transmitted light output port and outputting light having a wavelength included in a filter cutoff band among the modulated light as filter cutoff light, and the peak of the filter transmission band is set on a shorter-wave side from the peak of the spectrum of modulated light output from the directly modulated laser.

Abstract: An optical network unit includes an optical transmitter, an optical detector and a signal measurement module. The optical transmitter transmits an optical signal to an optical line terminal of a passive optical network system. The optical detector is utilized for monitoring the emission of the optical signal and transforming the received optical signal into a current signal. Then, the current signal is transformed into a voltage signal. The signal measurement module is connected to the optical detector for filtering and sampling the voltage signal and generating a sampling signal. The average output power of the optical transmitter can be obtained by averaging the voltage values of the sampling signal. Once the up-transmission data packet of the optical network unit exceeds the time interval of the allocated time slot, and the voltage values of the sampling signal have several points over a threshold, the optical transmitter is turned off.

Abstract: A method for monitoring an optical transmission line in which digital optical signals are transmitted bidirectionally between a first and a second end point of the transmission line. At the first end point of the transmission line the digital optical signal to be transmitted to the second end point is amplitude-modulated with a preset frequency, with the modulation amplitude being small relative to the amplitude of the digital signal. At the second end point of the transmission line a small fraction of the power of the received digital signal is overcoupled passively on the optical transmission line in the direction towards the first end point and is transmitted to the first end point together with the digital signal to be transmitted from the second end point to the first end point of the optical transmission line. At the first end point the amplitude-modulated component of the received digital signal is detected.

Abstract: According to one embodiment, a signal transmission circuit includes: a first electro optical converter converting a read electric signal to a first optical signal having an optional wavelength ?R; a first photo-electric converter configured to reconvert the first optical signal to the read electric signal; a second electro optical converter converting a electric signal to be recorded to a second optical signal having a wavelength ?W different from the ?R; a second photo-electric converter reconverting the second optical signal to the electric signal to be recorded; a first optical multiplexer/demultiplexer connected to the first electro optical converter and the second photo-electric converter, and multiplexing and demultiplexing the first and second optical signals; a second optical multiplexer/demultiplexer multiplexing and demultiplexing the first and second optical signals; and an optical transmission medium connected to the first and second optical multiplexers/demultiplexers, and transmits the multiplex

Abstract: The present invention provides an optical receiver that includes a monitoring unit with a function to prevent the unit from misjudging of the loss-of-signal state. In particular, the present invention is applicable to the monitoring unit that receives the signal to be judged from the processing unit posterior to the optical converting unit that couples with the processing unit via the capacitor. The signal reflects the second or higher order response lag due to the coupling capacitor. The monitoring unit of the invention generates the loss-of-alarm signal when the signal is continuously smaller than the first reference by a preset time and continuously greater than the second reference by the present time.

Abstract: In a network design apparatus, a full channel evaluator determines whether all wavelength channels for main signals can deliver the main signals of an existing optical network. When it is found that one or more wavelength channels cannot deliver main signals, a chromatic dispersion evaluator determines whether there are a specified number of wavelength channels that satisfy a specified chromatic dispersion condition. An optical signal-to-noise ratio (SNR) evaluator extracts a specified number of wavelength channels out of those satisfying the chromatic dispersion condition in descending order of optical SNRs thereof, and determines whether the extracted wavelength channels satisfy a specified optical SNR condition.

Abstract: Network elements are identified as being connected to optical nodes by instructing two network elements in a spectrum group of the CMTS to transmit at frequencies f1 and f2, respectively. Frequencies f1 and f2 are selected such that they produce intermodulation distortions (intermods) in the laser transmitter at f3 when combined. If intermods are produced which exceed a predetermined threshold, then the two network elements are determined to be on the same node. If the total power of the signal by the laser transmitter exceeds an impact threshold, then the test is stopped and new network elements are selected for testing.

Abstract: According to the WDM optical transmission system, for optical signals of respective wavelength in a WDM light propagated through a transmission path, a spectrum component at a center wavelength of each optical signal and a spectrum component in the vicinity of the center wavelength thereof are selectively attenuated by a spectrum correction optical filter, so that the WDM light is transmitted in a state where intensity of sideband components in the spectrum of each optical signal is relatively increased. As a result, even if spectrum width of the optical signal of each wavelength is limited when the WDM light passes through the band-limiting device on the transmission path, degradation of transmission characteristics caused by the attenuation of sideband components is reduced.

Abstract: An optical/electrical composite cable in which a first connector having an optical transmission unit is connected to a second connector having an optical reception unit via an electrical wire and an optical wiring line includes a state detection unit that detects a connection state of the first connector, a connection state of the second connector, a power supply state of a transmission-side electronic device connected to the first connector and a power supply state of a reception-side electronic device connected to the second connector, and an electrical power supply control unit that controls supply of electrical power to the optical transmission unit and optical reception unit according to the detected states.

Abstract: The present disclosure relates to a passive optical network (PON) and discloses a method and system for maintaining the PON where the optical line terminal (OLT) is provided with an optical power detection module for measuring the total power of optical signals received by the PON, and the optical network units (ONUs) are provided with an optical transmitter power supply module.

Abstract: The path selection and wavelength assignment to a selected path are performed by mapping the wavelength reach to the demand distribution (agile reach) resulting in a 50-60% increase in the network reach. The network reach is further increased (about 2.2 times) when on-line measured performance data are used for path selection and wavelength assignment. The connections may be engineered/upgraded individually, by optimizing the parameters of the entire path or of a regenerator section of the respective path. The upgrades include changing the wavelength, adjusting the parameters of the regenerator section, controlling the launch powers, mapping a certain transmitter and/or receiver to the respective wavelength, selecting the wavelengths on a certain link so as to reduce cross-talk, increasing wavelength spacing, etc.

Abstract: Methods and apparatus for optical-power control in an optical network employing wavelength-division multiplexed (WDM) optical-fiber links are devised to circumvent the effect of crosstalk caused by optical-power scattering. Each carrier signal is amplitude-modulated by an identifying tone, with the power of an identifying tone having a predetermined ratio to the power of its carrier signal. A fiber span within an optical-fiber link is tapped at a preferred monitoring point, and the power spectrum of the envelope of the tapped optical signal is measured. To estimate an individual carrier power, a temporary gain is applied and the power of a corresponding tone is measured. To control optical power of each wavelength carrier in several spans in the network, a network controller selects an order of processing the spans of interest, and selects the order of processing of each channel within each span.

Abstract: In embodiments of the present invention, an optical device tester performs stressed eye testing on several optical receivers and transmission and dispersion penalty testing on optical transmitters at a variety of data rates wavelengths using single mode optical signals and multimode optical signals using a variety of supply voltages and temperatures.

Abstract: One embodiment provides a system for performance monitoring in a passive optic network (PON). The system includes an optical line terminal (OLT) and an optical network unit (ONU). The OLT includes an optical transceiver configured to transmit optical signals to and receive optical signals from the ONU, and a performance monitoring mechanism configured to monitor performance of the PON based on received optical signals.

Abstract: A WDM system includes a plurality of P to P WDM systems connected for wavelength-multiplexing optical signals of a plurality of wavelengths, transmitting them to a transmission path, transmitting wavelength-division multiplexed light while performing amplification by using optical AMP in the transmission path, and subjecting the wavelength-division multiplexed light to wavelength isolation at the reception side. An OSC which is a monitoring control signal such as a normal optical signal is used closely within one P to P WDM system. However, by transmitting and receiving the OSC between a plurality of P to P WDM systems, it is possible to solve a problem at the system rise. Moreover, since accumulative OSNR data is transmitted up to the P to P WDM system of the final stage, it is possible to detect an accurate OSNR value and a leak ASE light quantity at the end side.

Abstract: Reduction in power consumption at low costs is realized by a system with apparatuses connected with each other. A switch device comprises transmission/reception unit each connected to each of apparatuses through a communication cable for transmitting/receiving a signal to/from each apparatus, and a connection switching unit for switching connection between the apparatuses by switching connection between the transmission/reception unit. Further provided are a reception state monitoring unit for monitoring a signal reception state of the transmission/reception unit, and a transmission stopping unit for executing signal transmission stopping processing according to a monitoring result obtained by the reception state monitoring unit with respect to other transmission/reception unit to which connected through that communication cable is other apparatus having a connection relationship with the apparatus to which the transmission/reception unit is connected through the communication cable.

Abstract: Apparatus and methods to monitor optical intensity within optical fibers in a substantially non-invasive fashion are disclosed. Optical monitors are comprised of thin, conductive coatings applied to transparent substrates and patterned to form pairs of resistive elements, one of which intersects an optical beam propagating through optical fiber cables. Systems of distributed optical monitors interconnecting optical fiber links enable automated monitoring of the optical status across a communications networks.

Abstract: The invention relates to an optical transmitting device. Particularly, the invention provides a loss-of-signal detecting device that detects a loss of an optical signal received by a terminal station or a relay station, in the order of an SD and an SF.

Abstract: Methods and systems for controlling power in a communications network are provided. In one embodiment, a method comprises reading a power level of a communication link; and, driving an attenuation control signal based on the power level of the communication link. When the power level is greater than or equal to a minimum supported power level, driving an attenuation control signal further comprises constraining the attenuation control signal to a calibrated range of a characteristic curve. When one or both of the power level is less than the minimum supported power level and a bit error rate is greater than a maximum error threshold, driving an attenuation control signal further comprises generating an attenuation control signal outside the calibrated range of the characteristic curve.

Abstract: In a passive optical network system, a parent station includes a reception circuit that receives an optical signal from each of child stations using a threshold used to identify if the optical signal is 0 or 1; a bandwidth setting unit that determines a time at which each child station sends an optical signal; a storage unit that stores thresholds and intensities of optical signals received from the child stations; and a control unit that sets a threshold, stored corresponding to a sending time, in,the reception circuit to control a reception of an optical signal. The control unit has a function that compares an intensity of a signal received from each child station at an optical signal reception time with information stored in the storage unit to detect and determine a fault in the child station or in the optical fiber connected to the child station.

Abstract: A method and device for determining in-band noise of an optical signal. The optical signal is split to produce two optical signal components, of distinct polarisation, such that the respective noise component in each signal component is uncorrelated. The optical signal components are converted to the electrical domain to produce electrical signal components. The signal component powers are equalised either in the optical domain or the electrical domain. The equalised electrical signal components are then subtracted together to cancel the correlated portions of the signal components (e.g. the data signal), such that only uncorrelated signal components (e.g. noise) are output for measurement.

Abstract: In an optical telecommunication system in which an intensity of an arriving optical signal is different for each packet, detected is an optical intensity for each packet with little error. For this purpose, contrived is to detect an average optical intensity across header parts for each packet by focusing on the fact that the header part comprising the preamble and delimiter of a packet is in a bit pattern which includes approximately the same numbers of “0” and “1”.

Abstract: Each of a plurality of semiconductor optical amplifiers operates as an optical gate switch and selects an optical signal indicated by a gate control signal from an optical gate switch control unit. A plurality of photodetectors monitor the power of an optical signal input through a corresponding input port. A VOA control unit calculates an amount of attenuation corresponding to each input port based on the power of each optical signal. A variable optical attenuator attenuates the selected optical signal according to the calculated amount of attenuation in synchronization with the gate control signal.

Abstract: An optical transmission apparatus includes a transmitting unit for transmitting an optical signal with a specified wavelength, a multiplexing unit for multiplexing the optical signal with the specified wavelength and an optical signal with a wavelength other than the specified wavelength and outputting the multiplexed signal as a wavelength division multiplexed optical signal, an optical amplifier for amplifying the wavelength division multiplexed optical signal outputted from the multiplexing unit, a level detecting unit detecting a variation of an optical power of the wavelength division multiplexed optical signal inputted to the optical amplifier, and a level adjusting unit for adjusting, when a variation of the optical power of the wavelength division multiplexed optical signal is detected by the level detecting unit, a transmitting power of the optical signal with the specified wavelength transmitted from the transmitting unit so that an output power becomes a level before the variation.

Abstract: An optical transmission apparatus for amplifying and relaying a wavelength-division-multiplexed optical signal includes (1) a variation-detecting unit which detects varying speed of input power of the wavelength-division-multiplexed optical signal and compares the varying speed with a set value, (2) an optical amplifying unit which amplifies the wavelength-division-multiplexed optical signal at a fixed amount of amplification, (3) a variable optical attenuating unit which variably attenuates the wavelength-division-multiplexed optical signal, (4) and a controlling unit which controls attenuation amount of the variable optical attenuating unit in accordance with the varying speed.

Abstract: 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.

Abstract: Provided are a signal-quality evaluation device and a signal adjustment method which require shorter evaluation time and which have high flexibility of application. A signal quality evaluation device 100 includes an optical component 110 and an optical output detector 120. In the optical component 110, an output optical power Pout is a function of an input optical power Pin, and this function Pout(Pin) has at least one maximum point. The optical output detector 120 detects the time-average power of light output from the optical component 110.

Abstract: Heavy users of a Multi-Dwelling Unit Optical Network Terminal (MDU ONT) continuing to use services, such as telephone, data and video, when the MDU ONT is operating from backup power unfairly use the power available from the battery backup power supply. In other words, a heavy user uses more than his share of the power available at the battery backup power supply. Example embodiments of the present invention eliminate such unfairness by associating with each user a separate battery backup power supply dedicated to support that user's services. Therefore, the heavy user will drain his battery more quickly than a light or moderate user. In situations when power from a user's battery backup power supply is not available and an emergency or priority service is requested, the MDU ONT may allocate power from other user batteries, or its own central battery, to support the service.

Abstract: A method is provided to calibrate a monitor photodiode that measures the optical output power generated by an optoelectronic transceiver module that includes a burst mode laser diode. The method includes disabling the power control loop that controls an average optical output power generated by the laser diode during a laser burst. A series of logic zero signals is applied to a data input of the transceiver module and the logic zero level of the optical signal generated by the burst mode laser diode while applying the series of logic zero signals is measured. The logic zero bias level applied to the laser diode is adjusted until the measured logic zero level of the optical signal reaches a first desired value. While maintaining the optical signal at the first desired value, a first value of a current generated by the monitor photodiode in response to optical energy received from a back facet of the laser diode is stored.

Abstract: An optical transmission apparatus comprises a preamplifier controlling unit for controlling a preamplifier so that amplified spontaneous emission including all wavelength bands of a wavelength-multiplexed signal beam is outputted toward a wavelength demultiplexing unit, with the wavelength-multiplexed signal beam not inputted, power monitors for monitoring optical powers of the amplified spontaneous emission fed from the preamplifier and wavelength-demultiplexed by the wavelength demultiplexing unit, and a determining unit for determining the continuity state of an optical propagation path of each wavelength component on the basis of a result of monitoring by the power monitors. The optical transmission apparatus allows the continuity test on optical propagation paths of channels including a channel not used at the time of a start of the operation to be made easier than the known techniques.

Abstract: A method for pre-emphasising transmitted signals in channels for multiplex signals along a transmission path comprising supply and/or branch points is provided. According to the method, relative degradations of the signal-to-noise intervals between transmitted signals via any category or group of channels—i.e. express and add or drop channels or add-drop channels are taken into account. A point-to-point link and for transparent optical networks may be used. To this end, the average signal powers of different channel groups are set relative to one another in order to obtain predetermined signal-to-noise intervals for each group. In addition, the signal-to-noise intervals within a channel group are equalized at their termination points. Regulation protocols for controlling the pre-emphasising steps are provided.

Abstract: A wavelength division multiplexing (WDM) device, an optical leakage prevention method, and a WDM communication system are disclosed. The WDM device includes a level adjusting unit for receiving an optical signal, for adjusting the optical power level of the received optical signal, and for outputting the level-adjusted optical signal; and a controlling unit for analyzing the optical power level of the optical signal output from the level adjusting unit, for controlling the level adjusting unit so that the optical power level of the output optical signal stays at a constant level, and for transitioning to an “off-state” when the optical power level of the output optical signal becomes less than a predetermined disconnection-detection threshold so that the level adjusting unit gives a predetermined attenuation to the input optical signal.

Abstract: In a TDMA optical network, a clock data recovery module uses signal oversampling and preamble correlation together with enhanced performance modules to extract additional data from the upstream transmission signal. Information including duty cycle, ONT power estimation, signal noise and jitter can be extracted from the upstream signal using digital logic and used to tune network components and/or alleviate network conditions.

Abstract: A method for estimating optical power in an optical channel includes determining a tunable filter full-width, FWF, by measuring a response of the tunable filter to a known signal and mapping the response to frequency. A portion of an optical channel is coupled to an input of the tunable optical filter. A peak power response, PR, and a full width tunable filter response, FWR, to the optical channel are determined by measuring a response of the tunable filter to the optical channel and mapping the response to frequency. A signal power, PS, is then calculated from the peak power response, PR, and a ratio of the full width tunable filter response, FWR, to the tunable filter full-width, FWF.

Abstract: In an optical communication network, optical communication nodes exchange information detailing power level variations to support management and administration of optical communications. This exchange of information permits nodes to determine aggregate power level variations over light paths to support operations such as selection from available light paths and configuration of optical communication characteristics.

Abstract: The present invention discloses methods for reducing power consumption in a PON while maintaining service continuity, the method including the steps of: providing an OLT operationally connected to at least one ONU; triggering a sleep request for at least one requesting ONU; upon receiving a sleep acknowledgement, activating a sleep mode for at least one requesting ONU according to a sleep period designated in the sleep request; and terminating the sleep mode according to the sleep period. Preferably, the sleep acknowledgement is transmitted from the OLT to the requesting ONU. Preferably, the sleep period is executed by a sleep command in the sleep acknowledgement. Preferably, the method further includes the step of: upon completion of the sleep period, transmitting buffered data traffic from the OLT to a sleeping ONU. Preferably, the step of transmitting is performed without the sleeping ONU being re-registered and without causing packet reordering.

Abstract: In a wavelength-division-multiplexing optical transmission system in which optical-node apparatuses that perform relay transmission of wavelength-division-multiplexed light are located at specified nodes in a main optical transmission path, an optical amplifier switches level control to constant-gain control when there is a notification of a change in the number of multiplexed wavelengths, and then after a specified amount of time restarts level control so that the level becomes a target level that corresponds to the actual number of wavelengths.

Abstract: Techniques for measuring optical modulation amplitude (OMA) are disclosed. For example, a technique for measuring an OMA value associated with an input signal includes the following steps/operations. The input signal is applied to a photodetector, wherein the photodetector is calibrated to have a given responsivity value R, and further wherein the photodetector generates an output signal in response to the input signal. The output signal from the photodetector is applied to a radio frequency (RF) power meter, wherein the RF power meter measures the root mean squared (RMS) power value of the output signal received from the photodetector. The OMA value associated with the input signal is determined in response to the root mean squared (RMS) power value measured by the RF power meter. The OMA value may be determined as a function of a factor F derived from a relationship between an amplitude of a data signal and the RMS value of the data signal.

Abstract: According to halt of a Raman pumping light source, a transmitting light power of a first light which is subject to receive a Raman gain is controlled to increase. In this state, a first input/output light power for a first light of an optical transmission line is measured, the first input/output light power being used for determining a reference of loss characteristic of the optical transmission line. A second input/output light power for a second light of the optical transmission line is measured, the second light not being subject to receive the Raman gain, the second input/output light power being used for determining a fluctuation of the reference.

Abstract: An optical transmitter that controls the extinction ratio by modulating a power level of an optical signal using a frequency spread tone. An electro-optic transducer driver generates an electrical signal that is to be converted into an optical signal. Meanwhile, a tone generator generates an electrical tone having a relatively narrow frequency spectrum. A frequency spreading circuit frequency spreads the electrical tone. A modulator modulates a power level of the electrical signal using the frequency spread electrical tone. An electro-optic transducer then converts the modulated electrical signal into a corresponding optical signal. An optoelectronic transducer recovers the modulated electrical signal by monitoring the optical signal. The tone is then recovered from the signal, and demodulated. The demodulated tone is then used to control the extinction ratio.

Abstract: Example embodiments include a method for monitoring an optical network. The method provides received network data to a network model, which determines if there is an inconsistency within the optical network. The network models include a statistical model and a detailed-physical model, both of which model amplifier physics.