Abstract: An optical transmission line monitoring device is provided including a device which calculates a management amount based on an optical intensity of returning light, a reference data storage device which stores reference management amounts beforehand, a detecting device which in response to the calculated management amount being of poorer quality than the reference management amount stored in the reference data storage device detects a distance, creates detection data based on the calculated management amount, and stores the created detection data in a detection data storage device, an alarm outputting device that creates alarm data based on the detection data created by the detecting device, and displays the created alarm data on a screen, an inputting device that inputs selection command data indicating that the alarm data displayed on the screen will not be output, and a removal data adding device that adds, to the detection data stored in the detection data storage device corresponding to the alarm data of

Abstract: An automated optical transport system is provided which provides for automatic discovery of system components, automatic inventory of system components, automatic topology detection, automatic provisioning of channels, and automatic characterization and tuning of system components and fiber. The invention provides automation capability through inclusion of management card capabilities at each station which communicates through a reverse propagating service channel. Dynamic and propagation direction independent segments are provided in conjunction with a token-based scheme to repeatedly tune, update and monitor the transport system.

Abstract: The location of a physical disturbance along an optical waveguide is determined by measuring different propagation times for the resulting phase variation to propagate to phase responsive receivers at ends of bidirectional signal paths. Each receiver can have a coupler that functions as a beam combiner and as a beam splitter inserting the opposite signal. On each receiving end, the coupler provides one or more detectors with signals from which phase related independent variable values are taken, processed and mapped to phase angles. Relative phase angle versus time is derived for each opposite signal pair and correlated at a time difference, i.e., a difference in propagation time from which the location of the disturbance is resolved. Polarization sensitive and polarization insensitive examples are discussed with various optical fiber arrangements.

Abstract: An optical transmission apparatus includes an optical add drop multiplexer (OADM) that adds/drops an optical signal to/from a transmission path. The optical transmission apparatus further includes a pump light multiplexer and a dispersion compensation fiber that are located downstream of the OADM on the transmission path. The optical transmission apparatus is configured to house a pump light source connectable to the pump light multiplexer to Raman amplify an optical signal in the dispersion compensation fiber.

Abstract: An optical wavelength controlling method and a system thereof for an optical wavelength division multiplexing transmission system, wherein a plurality of wavelengths of channels are multiplexed and transmitted by an optical transmitting unit, and the multiplexed wavelengths are divided into the wavelengths of the channels by an optical receiving unit, are disclosed. The optical wavelength controlling method includes: a step of reducing optical power of the wavelength of a target channel, and transmitting the wavelengths; a step of evaluating channel crosstalk based on a code error rate of a channel adjacent to the target channel, and detecting a shift of the wavelength of the target channel; and a step of compensating for the shift of the wavelength of the target channel.

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: 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: In one implementation, a system detects that a fiber within a fiber optic cable has failed and automatically causes a location of a faulty portion of the fiber to be identified in response to the detecting. In another implementation, a central office includes a first optical patch panel operably coupled to an optical fiber and a second optical patch panel configured to couple the first optical patch panel to a test device. The optical fiber is automatically coupled to the test device in response to one or more signals from a remote management device.

Abstract: An automated optical transport system is provided which provides for automatic discovery of system components, automatic inventory of system components, automatic topology detection, automatic provisioning of channels, and automatic characterization and tuning of system components and fiber. The invention provides automation capability through inclusion of management card capabilities at each station which communicates through a reverse propagating service channel. Dynamic and propagation direction independent segments are provided in conjunction with a token-based scheme to repeatedly tune, update and monitor the transport system.

Abstract: A system and method for detecting and compensating for thermal drift in an optical network in a manner that enables an increased number of optical channels to be used on a given optical medium, such as on a single optical fiber. A pair of narrow band, closely spaced optical signals from an optical transmitter function as a “temperature probe” signal. The two narrow band signals are centered within one passband of a filter of an optical device, such as an optical router. When the two narrow band signals are transmitted back to an optical receiver via the router, the magnitudes of the two signals are compared and a determination can be made as to the magnitude and direction of thermal drift of the passbands of the filter of the optical router.

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: An optical connection path surveillance device for a transparent optical network includes analysis means (80, 81) adapted to detect node signatures carried by an optical signal in transit at a point of said network, each node signature including information uniquely associated with a switching node of the network. The analysis means include calculation means (81) adapted to determine a number of hops from said detected node signatures and error detection means (81) adapted to compare said number of hops to a predetermined threshold in order to detect a routing error in relation to said optical signal if said threshold is exceeded. In one embodiment, a surveillance device detects looped paths on the basis of the detected node signatures.

Abstract: An optical transmission system comprises two optical fibers carrying optical signal traffic between two terminals, and a plurality of optical repeaters coupled to the two fibers each repeater having a permanently connected passive high loss loop back circuit between the two fibers. One terminal includes a transmitter, which launches a pulsed supervisory signal on a dedicated supervisory wavelength into one optical fiber, and a receiver, which detects a portion of the supervisory signal looped back from each repeater in order to identify the existence and location of faults in the transmission system. The pulsed supervisory signal is of sufficiently short duration such that portions of the signal returned from each repeater do not overlap with one another and interference with the counter-propagating traffic is avoided by utilizing a dedicated supervisory wavelength. Each return pulse is integrated sequentially by a single detector and processed by heterodyne reception and synchronous demodulation.

Abstract: The present invention provides an optical link monitoring system for the passive optical network. The system includes a master monitoring device connected to an optical line terminal and a plurality of response devices respectively connected to a plurality of optical network units. Through time division multiplexing technology, the master monitoring device broadcasts a predetermined instruction to the response devices to answer back predetermined optical signals in turn. The master monitoring device also measures the optical power of the returned predetermined optical signals and diagnoses the status of the optical links. The present invention also provides an optical link monitoring method.

Abstract: The invention concerns a transceiver module for an optical data network, comprising an optical interface for connection with an optical transmission line and an electrical interface for connection with a host board, wherein the electrical interface is suitable for providing the transceiver module with payload data to be sent on the optical transmission line and for providing the host board with payload data read from the optical transmission line, and further comprising monitoring means for monitoring the optical transmission line, which the transceiver module comprises an analyzing means for processing measuring data provided by the monitoring means in a statistical manner, and where the analyzing means is connected to the electrical interface for providing processed measuring data to the electrical interface. The inventive transceiver module is easy to install, and only a small amount of monitoring data needs to be transferred.

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: One apparatus embodiment includes a first light source, a second light source, and a receiver having a photodetector. The first light source emits a first signal at a nonvisible wavelength for data transmission. The second light source emits a second signal at a visible wavelength for fault detection when combined with the first signal for transmission over a fiber optic path. The receiver converts the first signal from the nonvisible wavelength to an electrical signal.

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: The present invention includes a fast algorithm to compute the pre-equalized waveform for simultaneous compensation of the self-phase modulation and chromatic dispersion experienced by a high-speed optical signal, e.g., at 10 Gb/s, and shows that it is used for an automatic self-adapting pre-equalization when the knowledge on transmission link details is inaccurate or incomplete.

Abstract: A system and method for transmitting an optical signal. The system includes a first optical transmitter capable of transmitting a first optical signal under one or more first operating conditions, and the first optical signal corresponds to a first wavelength. Additionally, the system includes a second optical transmitter capable of transmitting a second optical signal under one or more second operating conditions, and the second optical signal corresponds to a second wavelength. Moreover, the system includes an optical multiplexer coupled to the first optical transmitter and the second optical transmitter and capable of generating a multiplexed optical signal, a detection component configured to determine at least whether the first optical transmitter satisfies one or more predetermined conditions, and a tunable optical transmitter capable of transmitting a third optical signal. The third optical signal corresponds to a third wavelength.

Abstract: Jitter in a clock signal can cause communications faults in communications networks, such as in networks in which downstream nodes use recovered clock signals as timing for upstream communications. An embodiment of the present invention detects and compensates for jitter in a network by recovering a reference clock associated with communications signals between nodes, such as an Optical Line Terminal (OLT) and Optical Network Terminal (ONT) in a Passive Optical Network (PON). A local clock is synchronized with the reference clock. Jitter induced faults may be detected and compensated for by increasing the synchronization rate, then decreasing the synchronization rate until jitter induced faults begin to occur. A loss or change in a rate of communications errors occurring as a function of the synchronization rate may be monitored and reported to a system operator. Compensating for jitter by adjusting the synchronization rate provides for robust communications between network nodes.

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 communication device for detecting a defect in a standby optical fiber. An active optical output unit converts an electrical signal to an optical signal, and a standby optical output unit is provided as a substitute for the active optical output unit. An optical router is connected to the active optical output unit by an active optical fiber, and is also connected to the standby optical output unit by a standby optical fiber. The optical router outputs the optical signal received from the active optical output unit to the subsequent stage, and also outputs part of the optical signal to the standby optical output unit. A defect detector detects a defect in the standby optical fiber on the basis of the light level of the optical signal output from the optical router to the standby optical output unit through the standby optical fiber.

Abstract: Heretofore, it was necessary to individually locate an optical switch, an optical switch control circuit, and the like, before and after an optical transceiver that performs optical protection. As a result, costs and the space for implementation increase, and a delay in services is also caused, which were the problems. For the purpose of solving the above problems, the present invention provides a simple optical protection method used in an optical add-drop multiplexer. Add switches 105-1 through 105-N and drop switches 103-1 through 103-N for optical signals corresponding to each wavelength in an optical add-drop multiplexer 100 are made controllable independently of one another. Add switches and drop switches of the active-side and backup-side optical add-drop multiplexers are switched by optical switch control circuits 106-1 through 106-N respectively to make a detour around a failure so that the optical protection is achieved.

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: A node for managing an optical signal includes a first system optics card for providing channels to be transported over a first optical transport link and receives channels from a second optical transport link. Channels received over the second optical transport link are provided to an optical converter card for transport to a client device, for feedback onto the first optical transport link, or pass through to a second system optics card of the node. The first system optics card is capable of dropping network channels from the second transport link to associated client devices through optical converter cards and add client channels received from optical converter cards to the first transport link. The first system optics card may include one or more express input and output ports to couple with one or more other system optics cards in order to provide multiple degrees of communication capability.

Abstract: A loss of signal assert and de-assert level programming mechanism in an optical transceiver coupled to a host computing system. A control module is connected to the host so as to receive the programmable loss of signal level. A post-amplifier detects when the receive power drops below a loss of signal level. However, in this case, instead of the loss of signal level being static, a loss of signal level adjustment mechanism changes the loss of signal level detected by the post-amplifier as directed by the programmable loss of signal level received from the host. The loss of signal assert and de-assert levels may be calibrated by comparing receive power to the threshold for assertion and de-assertion of the loss of signal.

Abstract: This invention relates to a method for monitoring at least one section (50) of an optical fiber link (15,16), preferably a distribution section behind a passive distribution node (10-13), of a passive Optical Network, and a passive Optical Network being designed to perform the steps of the method.

Abstract: A communication network comprising at least one first terminal, at least one second terminal, a plurality of links, and at least first and second nodes. The first node is bidirectionally coupled to the first terminal through at least a first one of the links, and also is bidirectionally coupled to the second terminal through at least a second link and the second node. Preferably, the first node comprises a plurality of communication paths, each of which is coupled at a first end thereof to at least one corresponding first link. Second ends of the communication paths are all coupled to the second link, through a multiplexing device, and route signals between the first and second links. The first node also preferably comprises at least one alternate communication path having a first end coupled through the multiplexing device to the second link, at least one switch that is coupled to the alternate communication path, and a detector for detecting a failure in at least one of the communication paths.

Abstract: In an optical transmission apparatus controlling an optical output portion by a working optical output controller and a protection optical output controller, the optical output controllers separately generate (inverted) preset value signals corresponding to a common output preset value provided from outside, and perform an analog addition of a common optical output monitoring signal and the preset value signal with an integrating circuit. An optical output portion generates an optical output signal which is an optical input signal controlled based on an output of the wired-OR of the optical output controllers, and generates the optical output monitoring signal corresponding to the optical output signal. When the optical output monitoring signal exceeds the preset value signals, the optical output controllers substantially control input terminals of the integrating circuits respectively to a ground potential by using control circuits.

Abstract: Monitoring the physical layer of optoelectronic modules in a storage area network (SAN). In one example embodiment, a method for monitoring the physical layer of optoelectronic modules in a storage area network includes various acts. First, diagnostic data is gathered from a plurality of optoelectronic modules. Next, the diagnostic data is automatically analyzed to determine that any of the plurality of optoelectronic modules is operating outside acceptable parameters. Finally, a solution is automatically formulated to bring the one or more malfunctioning optoelectronic modules back inside acceptable parameters.

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: The distortion component of an optical signal received from an optical transmission system, such as an all-optical system, subject to noise and amplitude distortion components, can be evaluated by a method that utilises information derived from analysing the bit error ratio (BER) of the signal as a function of a movable threshold. The analysis is performed in high and low bit error ratio areas of the eye diagram used for data one/zero decision making. The intersections with the threshold axis (where BER=0.25) of extrapolations of the high and low bit error ratio values provide variables V1 and V2 which are divided (V1/V2) to obtain an estimate/prediction of the amplitude closure of the eye diagram resulting from amplitude distortion. The analysis is preferably carried out after Q conversion of the BER values. The method can also be extended to provide indications of Q, bit error ratio and optical signal-to-noise ratio within the signal.

Abstract: A telecommunications network component comprising: a processor configured to implement a method comprising: receiving an optical signal comprising at least one identification signal, the identification signal comprising a series of frequency portions that alternate in turn according to a frequency interval defined for each of the series of frequency portions, partitioning the identification signal by way of a plurality of windows, performing a Fast Fourier Transform (FFT) on each of the plurality of windows, determining which of the plurality of windows comprise a relative minimum number of frequency components, and detecting an optical channel based on results of the FFT performed on each of the plurality of windows that comprise the relative minimum number of frequency components.

Abstract: A channel switching function is added to a wavelength division multiplexing passive optical network (WDM-PON) system, which is an access optical network system, and the potential transmission rate is increased by combining wide wavelength tunable lasers and a time division multiplexing (TDM) data structure and properly using the necessary optical components. In addition, when the wavelength of a light source or an arrayed waveguide grating (AWG) changes, the wavelength is traced and the magnitude of a transmitted signal is maximized without an additional detour line using a loop-back network structure. Furthermore, fewer thermo-electric controllers (TECs) are required for stabilizing the temperature of an optical line terminal (OLT) using wavelength tunable lasers, each laser electrically changing its wavelength.

Abstract: The present invention is directed toward systems for conducting laser range and enabling optical communication between a plurality of entities and to the application of such systems in a secure covert combat identification system. In one embodiment, the present invention uses a novel laser system that generates high pulse rates, as required for optical communications, while concurrently generating sufficiently high power levels, as required by laser range finding operations. One application of the present invention is in enabling secure covert communications between a plurality of parties. Another application of the present invention is in tracking and identifying the movement of objects.

Abstract: An optical medium, whether inside or outside an internet/telecommunications backbone, is managed using a management signal at a wavelength which is distinct from wavelengths of service signals. A multiplexer multiplexes the management signal onto the optical medium, after which a demultiplexer demultiplexes the management signal for analysis. Performance of customer channels may be inferred from performance of the management signal.

Abstract: Information about optical amplifier ASE power is propagated down a link. Each amplifier along the link can learn of the ASE power at its input and take this input ASE power into account in controlling its own per channel output power. Each amplifier can also pass along to the next amplifier an indicator that represents its output ASE power taking into account both its input ASE power and own generated ASE power. Intermediate optical add/drop multiplexers (OADMs) adjust the ASE power indicator to account for losses and the spectral characteristics of each filter.

Abstract: A method and apparatus configured to incorporate system data for transmission as part of or concurrently with network data. The system data may comprise communication system data for use in controlling or monitoring a communication system. The system data may be is utilized to control or adjust the amplitude or intensity of the network data to thereby amplitude modulate the system data into or with the transmission of the network data. By monitoring the amplitude or intensity of the received network data signal, the system data may be recovered. An automatic gain control or bias loop may be monitored to detect the amplitude modulation of the network data. The system data may be encoded.

Abstract: A method for receiving an optical signal is included where an ingress signal is split into a first portion and a second portion. A relative delay is induced between the first portion and the second portion, which are optically interfered to generate at least one interfered signal. Quality criteria of a monitored signal at least based on the at least one interfered signal is monitored so that a relative delay based in the quality criteria may be adjusted.

Abstract: An optical transmission device includes: an attenuator that attenuates an optical signal from an adjacent optical transmission device; an optical element that is arranged downstream of the attenuator; a detector that detects a change in a characteristic of a transmission path; and a controller that adjusts, when the change is detected, an attenuation of the attenuator to keep the level of the optical signal input to the optical element at a predetermined level.

Abstract: A method for data-flow protection of an optical interface in data communication equipment includes: receiving an optical-signal from a source-neighboring device, then duplicating the received optical signal into two duplicated optical signals. One of the optical signals is sent to a protected device for processing. According to the protected device working status, either the optical signal having been processed by the protected device or the second duplicated optical signal is selected and sent to a destination-neighboring device. The device includes a first optical-signal duplicating unit and an optical-signal selecting unit. The first optical-signal duplicating unit is used for duplicating an optical signal, and the optical-signal selecting unit is used as a selector. The method and device proposed by the disclosure are independent to network topology and can protect data-flow reliably.

Abstract: An optical communication system includes a first optical device including a transmission optical switch and a controller coupled to the transmission optical switch, and a second optical device coupled to the first optical device via each of a first fiber and a second fiber. The transmission optical switch is configured to operate in one of a first mode associated with the first fiber and a second mode associated with the second fiber based on control signals generated by the controller. Moreover, the controller is configured to perform a non-revertive switching operation on the transmission optical switch based on the satisfaction or the non-satisfaction of a predetermined condition or a plurality of predetermined conditions.

Abstract: An optical network and method for managing a service across an optical network over a dedicated circuit between first and second service termination points include generating a service performance report message (PRM) at each service termination point. Each service PRM has service-specific information related to a performance of the service as determined by the service termination point generating that service PRM. Each service PRM identifies the service to which the service-specific information in that service PRM pertains. Each service termination point transmits the service PRM generated by that service termination point across the optical network over the dedicated circuit to the other service termination point through a service management channel of an optical transport facility.

Abstract: In an optical transmission apparatus, a unit includes a first connection section, a second connection section, a branching section, a first detection section, and a second detection section. The first connection section connects to a first component. The second connection section connects to a second component. The branching section is disposed at a preceding stage of the second connection section and outputs signal light to the first component through the first connection section. The first detection section determines whether the first component receives the signal light output from the branching section. The second detection section is disposed at a subsequent stage of the second connection section and detects the signal light.

Abstract: A method for receiving an optical signal is included where an ingress signal is split into a first portion and a second portion. A relative delay is induced between the first portion and the second portion, which are optically interfered to generate at least one interfered signal. Quality criteria of a monitored signal at least based on the at least one interfered signal is monitored so that a relative delay based in the quality criteria may be adjusted.