Abstract: Embodiments of the present disclosure describe a method and an apparatus for testing an optical network, which may be applicable to an integrated OTDR and the field of optical network technologies. The method includes obtaining a maximum test time of a single group test; dividing a total test time into at least two groups of single group test time that is not greater than the maximum test time when the total test time is greater than the maximum test time of the single group test; performing the single group tests in sequence according to each single group test time; and instructing optical network equipment to restore to a normal working state when the single group test time corresponding to each single group test ends.

Abstract: An optical line monitoring apparatus, including: a group information recording portion which records group information about to which splitter respective terminators are connected; a normal information recording portion which records intensities of reflected lights from a plurality of terminators in a state in which a failure is not occurring in optical lines; a monitored information recording portion which records intensities of reflected lights from the plurality of terminators in failure monitoring time; an attenuation amount determination portion which determines a terminator the reflected light intensity of which is attenuated compared with the corresponding reflected light intensity in normal information; and a control portion which determines, if the intensities of the reflected lights of all the terminators connected to the same splitter are attenuated by the same value, that a failure has occurred between the test apparatus and the splitter to which all the terminators are connected.

Abstract: An optical transmitter includes: a data generating unit configured to generate a plurality of modulating signals; a driver configured to amplify the plurality of modulating signals generated by the data generating unit; a phase shifter configured to control a phase of at least one signal among the plurality of modulating signals to be input to the driver; a plurality of optical modulators connected in series to each other, and configured to modulate an optical signal on a basis of each of the modulating signals amplified by the driver; an optical coupler configured to branch the optical signal modulated by the optical modulator arranged at a last stage in the series; a photodiode configured to detect the optical signal branched by the optical coupler and convert the optical signal into an electric signal; and a phase control unit configured to control an amount of phase control of the phase shifter to maximize an intensity of the electric signal converted by the photodiode.

Abstract: Embodiments include methods, apparatus, and systems for cable monitoring. One embodiment includes a method that receives data from an optical transceiver coupled to a cable and a RFID (radio frequency identification) device mounted to the cable. The data from the optical transceiver and RFID device is used to determine an operational status of the cable.

Abstract: There is provided an abnormal light cut-off system in which even when a high power light is inputted from an optical fiber connected to a user side apparatus by a malicious user or an accident, a trouble rate is low, the abnormal light is cut off at high sensitivity, and security is high.

Abstract: This disclosure relates to detection of optical fiber failure and implementation of protection switching in a passive optical network (PON). A protection switch determines whether there is an optical fiber failure in a fiber link between an OLT and a group of ONTs. In the case of an optical fiber failure, an optical fiber may be physically cut or damaged, causing the optical fiber link to be disabled. A protection switch may detect an optical fiber failure by determining a peak optical power of at least a portion of an upstream optical signal transmitted from one or more ONTs via the optical fiber link. If the peak optical power is less than a threshold value, the protection switch may detect a fiber failure. In response to a detected fiber failure, the protection switch may switch upstream and downstream PON transmissions from a primary optical fiber to a secondary optical fiber.

Abstract: Methods and systems for operating a physical layer device (“PHY”) in an Ethernet network include methods and systems for detecting active link partners and for selecting a mode of operation based on detected active link partners, without user intervention. The PHY monitors fiber link media and copper link media for active link partners. The PHY selects a mode of operation according to detected active link partners. For example, a serial gigabit media independent (“SGMII”) mode of operation is selected when an active copper link partner is detected and an active fiber link partner is not detected. Similarly, a serialize/deserialize (“SerDes”) pass-through mode of operation is selected when an active fiber link partner is detected and an active copper link partner is not detected. The PHY interfaces with the active copper link partner when the SGMII mode of operation is selected. Conversely, the PHY interfaces with the active fiber link partner when the SerDes pass-through mode of operation is selected.

Abstract: The present invention discloses a method for detecting dispersion, overcoming disadvantages of complex configuration and insensitivity to a tiny dispersion of the method and device for detecting dispersion in the prior art. The inventive method includes: obtaining a signal within a predetermined bandwidth range from an optical signal received; obtaining an operated value of power via an operation on the signal within the predetermined bandwidth range; and obtaining amount of system dispersion according to a corresponding relation between the operated value of power and the amount of system dispersion. A device for detecting dispersion is disclosed, including a photoelectric filter operational unit and a processing unit, where an output of the photoelectric filter operational unit is connected to an input of the processing unit. The device for detecting dispersion of the present invention is applicable to an adaptive dispersion compensation system. An optical signal transmission system is further disclosed.

Abstract: The present invention discloses a method for detecting dispersion, overcoming disadvantages of complex configuration and insensitivity to a tiny dispersion of the method and device for detecting dispersion in the prior art. The inventive method includes: obtaining a signal within a predetermined bandwidth range from an optical signal received; obtaining an operated value of power via an operation on the signal within the predetermined bandwidth range; and obtaining amount of system dispersion according to a corresponding relation between the operated value of power and the amount of system dispersion. A device for detecting dispersion is disclosed, including a photoelectric filter operational unit and a processing unit, where an output of the photoelectric filter operational unit is connected to an input of the processing unit. The device for detecting dispersion of the present invention is applicable to an adaptive dispersion compensation system. An optical signal transmission system is further disclosed.

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: An optical transmitter is provided for transmitting a wavelength multiplexed signal comprising an intensity modulation optical signal and a phase modulation optical signal through a transmission line. The optical transmitter includes a bit time difference given signal generator for generating at least two optical signals having a bit time difference therebetween, from the wavelength multiplexed signal. The optical transmitter further includes a wavelength multiplexed signal output unit to which at least two optical signals are input from the bit time difference given signal generator, and which generates and outputs a wavelength multiplexed signal in which the bit time difference was given between the phase modulation optical signal and the phase modulation optical signal.

Abstract: To produce a representation of the physical degradation in an optical communication network comprising transparent switching nodes (1, 2, 3, 4) mutually connected by optical links (11, 12, 21, 22, 31, 32, 41, 42), the method involves: Associating a pair of counter-directional optical links as a bi-directional link (10, 20, 30, 40), Providing at least one respective physical degradation parameter for each of said counter-directional optical links of said pair, Determining at least one physical degradation parameter characteristic of said bi-directional link from said physical degradation parameters of the counter-directional optical links of said pair, Storing a descriptor of the bi-directional link comprising said at least one physical degradation parameter characteristic of said bi-directional link.

Abstract: The present invention relates to methods and node entities for distributing Physical (PI) parameters used when establishing Optical Paths for user traffic by routing and wavelength assignment of optical channels carried in optical links of a Wavelength Switched Optical Network (WSON).

Abstract: The invention relates to a method for monitoring a detachable fiber-optic connection, especially in a fiber-optic transmission device or system, comprising the steps of transmitting a wanted optical transmission signal carrying information data to be transmitted to at least one fiber-optic connection, a predetermined portion of the power of said optical transmission signal being reflected at the at least one fiber-optic connection depending on the status and properties of the at least one fiber-optic connection, creating a detection signal by detecting said reflected predetermined portion of the power of said optical transmission signal, monitoring and evaluating the detection signal as a function of time and creating a “DETECT” signal if the detection signal or a signal derived from the detection signal reveals a characteristic change in its course in time. Further, the invention relates to a corresponding device adapted to realize this method.

Abstract: An image encodes processing parameters for a set of images. A wireless communication device optically receives and processes the received image to generate first image data. The image data represents the processing parameters. The wireless communication device processes the first image data to obtain the processing parameters. The wireless communication device then optically receives the set of images. The set of images encode second image data. The wireless communication device processes the optically received set of images based on the processing parameters to obtain second image data.

Abstract: Methods and apparatus for efficiently utilizing an optical control plane distinct from an electronic control plane to facilitate the setup of paths in a dense wave division multiplexing network are disclosed. According to one aspect of the present invention, a method includes receiving a probe arranged determine the optical feasibility of a first path, and determining a probability of success associated with the probe. The probability of success indicates a likelihood that the probe will be successfully routed on the first path to the destination, and is associated with a particular wavelength. A second path on which to route the probe is dynamically identified if the probability indicates a low likelihood of successful routing on the first path. Finally, the method includes determining if a notification associated with the probe has been received, and altering the probability of success based on the notification if the notification has been received.

Abstract: In particular embodiments, providing signal reachability information to a network includes establishing signal reachability information at a network node of the network. The signal reachability information describes attributes that affect reachability of an optical signal. The signal reachability information is inserted into an advertisement, and the advertisement is sent to network nodes of the network.

Abstract: The present invention is intended to provide an optical transmission system which is applicable not only to a known signal but also to an unknown signal, and has a high reliability at a low cost. A branching device branches an optical transmission output of a transmitter, and transmits the branched signals through different optical transmission channels. A polarization mode dispersion monitor monitors the degree of polarization mode dispersion from the optical transmission channels at the receiving end. A switch control circuit and a switch select a signal which is less affected by a deterioration in quality due to polarization mode dispersion, and outputs the selected signal to receiver 8. In this way, the probability of a deterioration in the quality of a signal due to polarization mode dispersion can be reduced for a transmission signal.

Abstract: A method and a device for an optical power budget in a passive optical network are disclosed in the present invention, wherein said method includes: acquiring a corresponding minimum optical link loss according to a transmission requirement of a passive optical network with a large splitting ratio or long distance (710); selecting an optical transmitter with large power and an optical receiver with high sensitivity as a combination of an optical transmitter of an Optical Line Terminal (OLT) and an optical receiver of an Optical Network Unit (ONU) in an optical link, as well as a combination of an optical receiver of the OLT and an optical transmitter of the ONU in the optical link according to the minimum optical link loss to compose a passive optical network system comprising the OLT, an Optical Distribution Network (ODN), and ONUs connected in sequence (720).

Abstract: A quantum correlated photon pair generating device includes a nonlinear optical medium that generates quantum correlated photon pairs from excitation light by spontaneous parametric fluorescence and generates auxiliary idler light from the excitation light and auxiliary signal light by stimulated parametric conversion. The excitation light and auxiliary signal light are generated separately, combined, and input simultaneously to the nonlinear optical medium. An optical demultiplexer separates the auxiliary signal light and the auxiliary idler light output from the nonlinear optical medium. The intensities of the output auxiliary signal light and auxiliary idler light are detected, and the intensity or wavelength of the excitation light or the temperature of the nonlinear optical medium is controlled to maintain the ratio of the detected intensities at a preset value. The rate at which the quantum correlated photon pairs are generated is thereby held steady.

Abstract: A transceiver assembly is provided for use in an optical telecommunications network. The circuitry arrangement in the transceiver of the present invention generates a ranging signal that is transmitted along the fibers attached thereto and then filters the return signal in an manner that eliminates virtually all of the noise effects found on the fiber to provide a highly reliable timing signal for an accurate delay calculation. A band pass filter is supplied in line before the input signal is allowed to pass to the ranging signal detector and comparator thereby allowing only a signal at the fundamental frequency of the input signal to pass, thereby eliminating false signal detect triggers.

Abstract: Light escaping from an optical path, for example via Raman or Rayleigh scattering, can provide information about how light flows in the path or about the optical path. The path can be a waveguide, an optical channel, or a fiber that may be attached to or integrated with a substrate, for example in a passive or active planar lightguide/lightwave circuit, photonic integrated circuit, semiconductor laser, or optoelectronic element. The escaped light can be color-shifted with respect to the primary light flowing along the path. The escaped light can leave the path at an angle that facilitates detection. Processing or analyzing the scattered light, for example with support of a computing device, can help evaluate the path and/or assess a light intensity pattern thereof, for example to aid design, engineering, testing, qualification, troubleshooting, inspection, manufacturing, etc.

Abstract: The present disclosure provides methods and systems for detecting small span loss changes in fiber optic networks. The present invention utilizes existing equipment without additional hardware to provide span loss measurements in a highly accurate manner. In an exemplary embodiment, the present invention utilizes power measurements associated with an optical supervisory channel (OSC) at both ends of a fiber span. These measurements are periodically sampled taking into account propagation delay along the fiber span. Further, these measurements are integrated or time-averaged to account for temporary fluctuations. The present invention can be utilized for intrusion detection (i.e., unwanted fiber taps), fiber degradation, and fiber aging performance. The present invention satisfies the criteria for a feasible (i.e., makes use of current architecture), cost-effective (i.e., does not require additional hardware), and highly accurate solution (i.e., capable of detecting span loss changes of 0.01 dB or 0.03%).

Abstract: A method for monitoring wavelength-division multiplexed (WDM) signal for detecting signal drift of objective signals, including generation of one or more objective signals and a guard signal. The guard signal has a wavelength that is within a range defined by a guard channel. The first and second objective signals and the guard signal are wavelength-division multiplexed to generate a wavelength-division multiplexed signal. The first objective signal, the second objective signal, and the guard signal are assigned to a first multiplexed objective channel, a second multiplexed objective channel, and a multiplexed guard channel, respectively. The wavelength-division multiplexed signal is received by a monitor and then the error rate of the multiplexed guard channel is determined.

Abstract: When transmitting in higher-order modes (HOMs), the chances of dielectric breakdown in the bulk glass can be reduced by judicious selection of the mode of transmission. Since energy distributions in the HOM profile change with the mode order, one can calculate the peak intensity for any given HOM. Correspondingly, one can calculate whether any portion of the transmitted pulse will exceed the breakdown threshold for the optical fiber through which the HOM signal is being transmitted. Should the calculated energy exceed the dielectric breakdown threshold, another HOM with a lower peak intensity can be selected for signal transmission. Disclosed are systems and methods for selecting an appropriate HOM to reduce the likelihood of dielectric breakdown.

Abstract: The present invention relates to a light source and detecting device thereof includes: a housing; a printed circuit board; an optical fiber connector; a laser diode; a laser driving module; a light coupling device; a light detecting module; an analog-to-digital converter; a micro controlling device; a stroke switch and a displaying device; when the stroke switch is pressed, the light detecting module is activated according to a determination made by the micro controlling device then a light signal coupled by the light coupling device is detected by the light detecting module, then the signal is displayed on the displaying device after being converted by the analog-to-digital converter or the laser diode is driven by the laser driving module and a laser source is therefore emitted.

Abstract: Various example embodiments are disclosed. According to one example embodiment, a method may include transmitting a semiconductor laser-generated optical signal from a first end of a multi-mode fiber (MMF) optical link to a second end of the link. The optical signal may have a reference bandwidth at the first end of the link. The method may further include converting the optical signal to an electrical signal. The method may further include analyzing the electrical signal with an electronic dispersion compensator to determine an effective modal bandwidth (EMBW) of the received optical signal. The method may further include analyzing the electrical signal with an electronic dispersion compensator to determine an intersymbol interference (ISI) penalty of the optical link.

Abstract: A method is provided for measuring polarization dependent loss in an optical transmission system. In the method, a first optical signal is generated, and a polarization of the first optical signal is altered over time. The first optical signal is combined with a second optical signal from the optical transmission system to yield a combined optical signal, which is coherently detected to yield a radio frequency signal. A power of the radio frequency signal is measured. The measured power of the radio frequency signal is processed to generate an indication of the polarization dependent loss of the optical transmission system.

Abstract: An apparatus and communication method that provide for communicating information on a standardized link compliant with a published standard and communicating information on a private link capable of operation at a throughput higher than maximum throughput of the published standard. The apparatus and method further provide for monitoring private link performance and increasing information throughput on the private link above the maximum standard throughput by an amount determined by the monitored private link performance.

Abstract: The present invention provides methods and systems for efficiently computing optimal optical launch powers for meshed optical networks. The present invention can be utilized to find optimal launch powers for multiple wavelengths in a meshed dense-wave division multiplexed (DWDM) system. Generally, the present invention ensures Q exceeds a threshold for OSNR, and then the launch powers are optimized based on nonlinear penalties. If Q is below the threshold, DWDM equipment changes/additions are incorporated to provide adequate OSNR. The present invention provides a computationally efficient mechanism to optimize launch powers in 10 Gb/s, 40 Gb/s, 100 Gb/s, etc. highly-meshed optical networks.

Abstract: The present invention relates to a system for sensing of a disturbance on an optical link. Data traffic from an optical source with a short coherence length is transmitted along the link to a receiver station on one or more of a plurality of time-division-multiplexed channels. One of the channels is used to transmit encoded phase information relating to the phase characteristics of the optical source output. At the receiver station, the actual phase characteristics of the arriving light from the optical source is compared with the encoded phase information. Since a physical disturbance of the link is likely to alter the actual phase characteristics of the arriving light but not the encoded phase information, it is possible to determine if a physical disturbance has occurred. The system can conveniently be used to monitor an optical link carrying communications traffic.

Abstract: Some optical communications networks include one ingress fiber, an n-way signal coupler, and n egress fibers, where each fiber may carry signals in one or both directions. A method and apparatus for testing and monitoring data communications immediately before and after the coupler is provided. Benefits include improved ability to identify and locate system faults, and improved ability to monitor data quality and content.

Abstract: 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.

Abstract: A method and circuit are provided for implementing reduced signal degradation for fiber optic modules, and a design structure on which the subject circuit resides. Responsive to a detected signal input, an optical misalignment calculation is performed. A voltage potential for a lens shape control is selected responsive to the optical misalignment calculation. An optical signal loss calculation and threshold compare are performed. Responsive to the optical signal loss calculation less than the threshold, the lens shape and voltage potential are fixed.

Abstract: The present invention provides a method for determining the bandwidths of optical fibers, wherein the method provides the coupling of light with a first optical power and a first modulation frequency into an optical fiber, as well as measuring a first signal level as a function of the optical power of the light of the first modulation frequency, coupling light with the second optical power and a second modulation frequency into the optical fiber, measuring a second signal level as a function of the optical power of the light of the second modulation frequency, and determining the bandwidths of the optical fibers as a function of the first and second coupled optical [power and/or] the measured first and second signal levels while using a predetermined specification that describes the frequency-dependent attenuation response of the optical fiber, wherein the first and the second modulation frequencies have essentially the same value.

Abstract: The invention relates to a method of operating an optical transmission system (100a, 100b, 100c), wherein at least one optical data signal is transmitted over an optical transmission link (120), which particularly comprises at least one optical fiber (120a). The inventive method is characterized by modulating (200) said data signal with a test signal (s) having a predetermined modulation frequency fmod to obtain a modulated data signal (Pin), by receiving (210) a reflected portion (Pback) of said modulated data signal (Pin), and by determining (220) a fiber quality measure (a) depending on said received reflected portion (Pback) of said modulated signal (Pin).

Abstract: The present invention provides methods and systems for efficiently computing optimal optical launch powers for meshed optical networks. The present invention can be utilized to find optimal launch powers for multiple wavelengths in a meshed dense-wave division multiplexed (DWDM) system. Generally, the present invention ensures Q exceeds a threshold for OSNR, and then the launch powers are optimized based on nonlinear penalties. If Q is below the threshold, DWDM equipment changes/additions are incorporated to provide adequate OSNR. The present invention provides a computationally efficient mechanism to optimize launch powers in 10 Gb/s, 40 Gb/s, 100 Gb/s, etc. highly-meshed optical networks.

Abstract: Monitoring an optical signal comprises sampling the optical signal from two or more distinct tap points to retrieve a sample set. Multiple such sample sets are obtained over time. A joint probability distribution or phase portrait of the sample sets is assessed for indications of optical signal quality. The tap distinction can be polarization, for example to determine OSNR, or frequency. The tap distinction can be a time delay, which can enable diagnostic differentiation between multiple impairments, such as OSNR, dispersion, PMD, jitter, Q, and the like. Machine learning algorithms are particularly suitable for such diagnosis, particularly when provided a two dimensional histogram of sample density in the phase portrait.

Abstract: Described is a method of transmitting an optical signal in an optical transmission system. The method comprises: providing a length of an optical fiber having a zero chromatic dispersion wavelength, wherein the optical fiber belongs to an optical fiber group and wherein the optical fiber group comprises optical fibers having a zero chromatic dispersion wavelength comprised within a wavelength range; estimating a tolerated chromatic dispersion range; and transmitting the optical signal over the length of optical fiber at a first transmission wavelength.

Abstract: An optical signal quality monitor device includes a local oscillator that generates a local oscillation signal, with which a mixer mixes an input optical signal to output a mixed signal, of which at least one beat component a filter that extracts. An intensity detector detects intensity of the extracted beat component. The monitor device may thus accurately and rapidly monitor the quality of an input optical signal transmitted even at a higher bit rate.

Abstract: An apparatus for measuring the characteristics of an optical fiber is provided. An optical pulse generator generates, from a coherent light, first and second optical pulses having a time interval which is equal to or shorter tan a life time of an acoustic wave in the optical fiber. A detector couples the coherent light with a Brillouin backscattered light which includes first and second Brillouin backscattered lights belonging to the first and second optical pulses respectively, thereby generating an optical signal. The detector further converts the optical signal into an electrical signal. A signal processor takes the sum of the electrical signal and a delay electrical signal which is delayed from the electrical signal by a delay time corresponding to the time interval, thereby generating an interference signal, and finds the characteristics of the optical fiber based on the interference signal.

Abstract: The present invention relates an optical waveform measuring apparatus designed to eliminate the polarization dependency of an intensity correlation signal without a polarization diversity arrangement. The apparatus comprises a sampling light outputting unit for outputting a sampling light pulse to sample light under measurement, a sampling result outputting unit for developing a nonlinear optical effect stemming from the light under measurement and the sampling light pulse from the sampling light outputting unit to output light corresponding to a result of the sampling of the light under measurement, and a polarization state control unit for, before the start of the measurement of the light under measurement, carrying out control on the basis of a power level of the light from the sampling result outputting unit so that a polarization state of the light under measurement, which is to be inputted to the sampling light output unit, is placed into a predetermined state.

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: A method for two or more optical transceivers coupled to each other by an optical link to optimize communication over the optical link. A first transceiver generates electrical data that represents an operational parameter for optimization. The transceiver then converts the electrical data into an optical signal and transmits the optical signal over the optical link to a second transceiver. The second transceiver recovers the electrical data from the optical signal and uses the recovered electrical data to change characteristics of the optical signal transmitted by the second transceiver.

Abstract: A fiber cable distortion detection system includes a broadband source, an optical source fiber disposed in optical communication with the broadband source, an optical fiber under test (FUT) disposed in optical communication with the optical source fiber and an optical spectrum analyzer disposed in optical communication with the optical source fiber. The system combines the refection of the distortion with the reflection from the source/FUT interface using a 1×2 fiber coupler, the location of the distortion is precisely determined with high resolution by the spectrum of the combined signal. The system is miniaturized to the size of a hand-held device suitable for use in airplane cable plant installation or in an environment where space is limited.

Abstract: A component for an optical communication network comprises a source (6) for an optical communication signal, an output port (11) for outputting the optical communication signal on an optical transmitting fiber (1), a light sensor (14; 15) and an optical circulator (9) for transmitting the optical communication signal from the source (6) to the output port (11) and for transmitting light reflected or received from outside at the output port (11) to the light sensor (14; 15). The light sensor (14, 15) has an evaluation circuit (13) connected to it for detecting a time delay between a time marker of a light signal from the source and the corresponding time marker of the light arriving at the light sensor (14; 15).

Abstract: During initial start-up of an optical communication system, an ASE reference span loss is calculated based on transmitting power and received power of ASE light generated by an optical amplifier, and an OSC reference span loss is calculated based on the transmitting power and the received power of OSC light. During normal operation of the optical communication system, a span loss is calculated using the OSC light, and an amount of change in the span loss representing a difference between the span loss and the OSC reference span loss is calculated. A current span loss between a transmitting station and a receiving station is calculated by adding the amount of change in the span loss to the ASE reference span loss.

Abstract: An apparatus and methods for testing a passive optical network with regard to fiber connectivity and attenuation losses, and with regard to the proper operation of packet-based communication protocols thereon.

Abstract: In an optical amplifier, an input light is supplied to one end of an optical fiber connected to an output port, and the power of a light in an opposite direction which is input to the output port from the one end of the optical fiber, is measured, thereby obtaining a stimulated Brillouin scattering (SBS) occurrence threshold in the optical fiber based on the measurement result. Then, using the SBS occurrence threshold, a relation between the input light power and an occurrence amount of the self phase modulation (SPM) or the like in the optical fiber is obtained to be reflected on a control of the optical amplifier, so that an occurrence of the SPM or the like in the optical fiber is suppressed. As a result, it becomes possible to accurately measure, with a simple configuration, the nonlinear optical properties of the optical fiber actually connected to the output port of the optical amplifier, so that the optical S/N ratio degradation due to a nonlinear optical effect can be effectively suppressed.

Abstract: An optical sensor system comprises one or more optical sensor devices, a master device and an electrical bus connecting the sensor devices to the master device. The bus comprises a signal daisy chain for the transmission of synchronization events. The sensor devices are adapted to detect a synchronization event at a signal input terminal, to time an optical activity based on this synchronization event and to provide at a signal output terminal a synchronization event delayed by an offset time with respect to the detected synchronization event. A property of the synchronization events provided by the sensor devices is indicative of an output value of the respective sensor device, corresponding to a state of an optical section to which the sensor is sensitive.