Abstract: Systems and methods for detecting leakage in a cable network system are disclosed. In at least some illustrative embodiments, a system may include a digital tagger operable to generate a digital tag including a chirp signal configured to be placed on a downstream signal path of the cable network system, and a cable network test instrument configured detect the digital tag in wireless signal data received from the cable network system when a point of ingress is presented in the cable network system. The network test instrument may be operable to provide a user-perceptible indication when the digital tag is detected to inform a technician or other user that a flaw in the cable network system is nearby.

Abstract: A packet network includes a plurality of network elements interconnected to one another via a plurality of links, and systems and methods include, responsive to detecting a signal degrade condition on a link in the packet network, advertising the signal degrade condition on the link; maintaining a Traffic Engineering database which includes signal degrade condition status based on the advertising; and, responsive to path computation through the packet network, determining a best path considering the signal degrade condition status of the plurality of links. The systems and methods include further include, responsive to detecting the signal degrade condition on the link has cleared, advertising the signal degrade condition has cleared on the link.

Abstract: Examples herein relate to optical systems. In particular, implementations herein relate to an optical system including a bidirectional optical link such as an optical fiber. The optical system includes a resonator tuned to filter a resonant wavelength of light emitted by an optical source. The optical source may be configured to emit light having multiple wavelengths, and the resonator may be configured to receive light emitted by the optical source. The optical system may further include a photodetector to receive the resonant wavelength and measure a power of the resonant wavelength. The optical system may further include a controller coupled to the optical source. The controller may receive the measured first power of the resonant wavelength and change the state of the optical source when the measured power of the resonant wavelength is outside a per-wavelength threshold range.

Abstract: Methods, systems, and apparatus for hosting an optical line terminal (OLT) bonding engine are disclosed. In one aspect, packet data for transmission over a passive optical (PON) is selected. A transmission wavelength assigned to the packet data is identified. A particular OLT is selected from among the additional OLTs to transmit the packet data over the PON based on the corresponding wavelength of the particular OLT matching the identified transmission wavelength assigned to the packet. The packet data is formatted based on the particular OLT. The formatted packet data is transmitted to the particular OLT for transmission over the communications interface.

Abstract: A method comprises receiving, at a plurality of optical distributors of a photonic chip, optical energy from a plurality of primary laser sources. Each of the optical distributors receives optical energy from a respective primary laser source at a respective first input. The method further comprises detecting a failed primary laser source of the primary laser sources using control circuitry of a sparing system. The sparing system further comprises one or more secondary laser sources configured to provide optical energy to respective second inputs of the optical distributors. A first one of the secondary laser sources is optically coupled with at least two of the optical distributors. The method further comprises controlling, using the control circuitry, a first one of the secondary laser sources to selectively provide optical energy to the optical distributor whose first input is optically coupled with the failed primary laser source.

Abstract: This disclosure relates to optical line system equipment, which enables wavelength addition for long haul transmission. The system is configured to prevent contention of wavelengths added into a multiplexer. For example, an optical wavelength combiner, such as a multiplexer, may include components that are configured to detect potential collisions between existing wavelengths and a newly added wavelength, and block the addition of the conflicting wavelength while alerting the operator.

Abstract: An optical add/drop multiplexer branching apparatus is provided in the embodiments of the present invention, where the optical add/drop multiplexer branching unit includes: a trunk input end, a branch input end, a trunk output end, a branch output end, an optical add/drop multiplexer, a first coupler, a first detection circuit, and a control circuit, where the optical add/drop multiplexer includes an optical switch. A detection circuit detects whether a fault occurs in a trunk, and in a case in which a fault occurs in the trunk, a working mode is switched from a first working mode to a second working mode, to implement automatic redundancy on the trunk and ensure normal communication on a branch.

Abstract: Apparatuses are disclosed including a node having a switch for communicating traffic from input interface to output interface; and a control module, located proximate to the input interface, output interface and switch, comprising a communication interface configured to connect to a third communication link external to the node and having a processor accessing network node configuration information and being configured to compute a path to a destination node through the output interface with the network node configuration information and also configured to be switched from a first state in which the processor provides first instructions to the switch to configure the switch to communicate the traffic from the input interface to the output interface, to a second state in which the processor provides second instructions, received via the communication interface, to the switch to configure the switch to communicate traffic from the input interface to the output interface.

Abstract: A method for bandwidth management in an optical broadcast network includes signaling, for a new optical broadcast service, from an originating node to all nodes in the optical broadcast network, wherein the signaling identifies a wavelength or portion of spectrum associated with the new optical broadcast service; at each of the nodes, checking for contention by the new optical broadcast service; responsive to identifying contention at one of the nodes, signaling the identified contention back to the originating node; and responsive to no contention at any of the nodes, processing the signaling, storing an update of the new optical broadcast service, and either forwarding the signaling to peer nodes or terminating the signaling.

Abstract: A method for bandwidth management in an optical broadcast network includes signaling, for a new optical broadcast service, from an originating node to all nodes in the optical broadcast network, wherein the signaling identifies a wavelength or portion of spectrum associated with the new optical broadcast service; at each of the nodes, checking for contention by the new optical broadcast service; responsive to identifying contention at one of the nodes, signaling the identified contention back to the originating node; and responsive to no contention at any of the nodes, processing the signaling, storing an update of the new optical broadcast service, and either forwarding the signaling to peer nodes or terminating the signaling.

Abstract: In some embodiments, an apparatus includes an optical transceiver system that includes a set of optical transmitters and a backup optical transmitter. In such embodiments, each optical transmitter from the set of optical transmitter can transmit at a unique wavelength from a set of wavelengths. The backup optical transmitter can transmit at a wavelength from the set of wavelengths when an optical transmitter from the set of optical transmitters associated with that wavelength fails. In other embodiments, an apparatus includes an optical transceiver system that includes a set of optical receivers and a backup optical receiver. The backup optical receiver can receive at a wavelength from the set of wavelengths when an optical receiver from the set of optical receivers associated with that wavelength fails.

Abstract: The present invention provides an improved optical communication network (300) that utilizes an apparatus of optical channel protection. The apparatus for optical channel protection of the present invention including a transmitting end network switch (200), a first and a second receiving end network switch (201, 202), a plurality of wavelength tuneable transmitting end transponders (400, 401 . . . 405), a plurality of wavelength tuneable receiving end transponders (400?, 401? . . . 405?), a transmitting end controller (10a) connected to a network monitoring and control system (100a) and a receiving end controller (10b) connected to said network monitoring and control system (100a). The present invention utilizes a method of optical channel protection that can be broadly categorized under optical multiplex switching.

Abstract: A multi-path provisioning scheme is provided to ensure full protection while reducing or minimizing resource overbuild. A signal to be provisioned is divided at a source node into a plurality of sub-signals that are independently routed from the source node to a destination node. Bandwidth for back-up traffic B is allocated in addition to bandwidth for primary traffic T. In some embodiments, the initial bandwidth B of the backup traffic equals the bandwidth of the primary traffic. The T+B traffic is initially distributed so that no link carries more than B traffic. The traffic distribution pattern is then iteratively revised to reduce the bandwidth requirements for the backup traffic while still meeting requirements for protection.

Abstract: A node of an optical transport network system transmits optical wavelengths to an adjacent node through an operational line. An apparatus for protection switching of the optical transport network system transmits only an optical channel with a fault among a plurality of optical channels composed of flexible optical channel data units in an optical wavelength of the operational line, via a reserve line.

Abstract: The present invention provides a method and apparatus for automatically restoring node resource state in the Dense Wavelength Division Multiplexing Based Automatic Switched Optical Network (WSON) system. This method comprises the following steps: using each node in the WSON system as an initiation node and notifying the resource state of the initiation node to a neighboring node; the neighboring node comparing the received resource state of the initiation node with the resource state of the present end; and under the condition that the resource state of the initiation node and that of the neighboring node are inconsistent, according to the actual resource state, determining one of the initiation node and the neighboring node to be the node whose resource is occupied, and automatically releasing the resource of the node. The present invention also provides an apparatus for automatically restoring node resource state in the WSON system.

Abstract: A method, a network, and a node each implement the transmission of Automatic Protection Switching (APS) switching coordination bytes across an OTN network. A working signal and a protection signal are received, one of which is designated as an active signal. The active signal is encapsulated in an Optical channel Data Unit (ODU) signal. APS switching coordination bytes from the working and protection signals are placed in an overhead segment of the ODU signal. The ODU signal is transmitted into and received from an Optical Transport Network (OTN) network. The working and protection signals are recreated based on the active signal encapsulated in the ODU signal and the APS switching coordination bytes in the overhead segment. The recreated working and protection signals are transmitted. In this manner, a single ODU signal may be used to transmit both the working and protection signals.

Abstract: An Optical Line Termination (OLT) system in a multi-wavelength Passive Optical Network (PON) includes a protection port for protecting a set of OLT ports without the use of a physical switch. The protection port has a tunable transceiver. The OLT system detects a failure of one of the OLT ports, which was originally adapted to transmit downstream traffic to a subset of ONUs on a downstream wavelength and to receive upstream traffic from the subset of ONUs on an upstream wavelength. In response to the detection, the OLT system tunes the protection port to the downstream wavelength for transmission and to the upstream wavelength for reception, and resumes communication between the OLT system and the subset of ONUs through the protection port instead of the OLT port.

Abstract: A optical transmission system includes light sources generating light of at least two wavelengths, where any two adjacent wavelengths are separated by less than 10 nm. The wavelengths fall within the zero dispersion zone of an optical fiber, and may be shifted by 1 nm or less to reduce crosstalk effects.

Abstract: A method and apparatus for determining if an optical input signals has been interrupted and responsively replacing an interrupted optical input signal with a replacement optical signal having a similar optical profile (e.g., such as a loopback between OADMs within a backbone network), thereby insuring that transient-induced high speed optical amplifier adjustments are avoided.

Abstract: The optical transmission device includes an N×N optical switch, an optical packet receiver and an optical packet generation unit. The N×N optical switch transmits data in which a plurality of optical signals each having a different wavelength is multiplexed. The optical packet receiver detects change in the number of wavelengths of optical signals constituting the data. The optical packet generation unit generates, when the change is detected by the optical packet receiver, data to be transmitted by the N×N optical switch, using optical signals for the number of wavelengths after the change.

Abstract: When a failure occurs in operational transmission multiplexing transponders 6-1 to 6-N, a wavelength multiplexing optical transmission system carries out selection switching control on N×1 optical switches 5-1 to 5-m and (N+1)×N optical switches 11-1 to 11-m to transmit a wavelength-multiplexed light signal by using reserve transmission and reception multiplexing transponders 6-R and 10-R, thereby sidestepping the failure.

Abstract: Embodiments of the disclosure are directed to optical dark section conditioning. An embodiment generates at least one of a broadband noise or signal at the head end of a section for a first module of the section; and operates all other modules of the section in gain control mode.

Abstract: An apparatus switches paths in a wavelength-multiplexing network in which a first number of wavelengths each used for a path to transmit an optical signal are multiplexed into an optical fiber. The apparatus includes an entire switching unit and a second number of individual switching units where the second number is smaller than the first number. The entire switching unit is configured to perform a path-switching process for switching a path, simultaneously on all the first number of wavelengths when failures have occurred for all the first number of wavelengths. The second number of individual switching units are each configured to perform the path-switching process individually on one of a third number of wavelengths included in the first number of wavelengths when at least one failure has occurred for the third number of wavelengths where the third numbers is smaller than the first number.

Abstract: A method includes detecting wavelength collision including identifying a pair or pairs of ONTs that transmit the colliding wavelengths and recovering from collision wherein wavelengths of the pair or pairs of ONTs that cause collisions are re-adjusted to eliminate the collision.

Abstract: Optical network protection devices and protection methods including: a working line; a protection line; a determination module configured to determine the protection type of optical network; a first judgment module configured to judge whether the working line is normal according to performance parameter values of service signal in the working line and switching conditions configured for multiplexing section protection when the protection type of optical network is the multiplexing section protection; a second judgment module, configured to judge whether the working line is normal according to performance parameter values of service signal in the working line and switching conditions configured for channel section protection when the protection type of optical network is the channel section protection; a switching module, configured to take the service signal in the protection line as an output signal when working line is abnormal.

Abstract: OSUs 1 to N are connected to a plurality of PON lines respectively. A control unit performs processing for registering a plurality of subscriber devices connected to the plurality of PON lines respectively and processing for allocating a bandwidth. In addition, the control unit switches an OSU while a state of registration of the plurality of subscriber devices is maintained, by changing a communication path between the plurality of PON lines and a plurality of OSUs 1 to N.

Abstract: This concerns a protected long-reach PON having a plurality of terminals connected to a distribution network that is fed by both a main and back up feed, each feed including a head end and a repeater. The back up head end had access to a ranging table with data previously obtained by the main head end, thereby speeding up the switch over in the event of a fault with the main feed. In one embodiment, the repeater has a virtual ONU therein, allowing the back up repeater to be ranged by the back up head end, thereby yet further speeding up the ranging procedure. The main and back up repeaters are sufficiently equidistant from the distribution network to allow the back up head to perform normal scheduling without performing a ranging operation on each of the terminals, even if the different terminals transmit at slightly different wavelengths. This is achieved using the ranging information obtained with regard to the back up repeater.

Abstract: Systems and methods for distributing signals in an optical network are disclosed. In accordance with one embodiment of the present disclosure a method for distributing signals in an optical network comprises combining input signals into one or more output signals, determining, an availability status of optical lanes for carrying the output signals and distributing the output signals to optical transmitters associated with the optical lanes if the availability status indicates that the optical lanes are available.

Abstract: An optical network system that performs transmission of N:1 protection includes a node that includes transmission-side operating muxponders that multiplex client signals for every M-channel signal bundle and convert multiplexed signals into optical signals having different wavelengths, transmission-side optical couplers that branch the client signals into two channels of operating and redundant, transmission-side optical switches each selecting one channel from redundant signals as a redundant client signal, and a transmission-side redundant muxponder that performs a predetermined transmission-side process according to an accommodation mode set on the redundant client signal and then multiplexes the redundant client signals, converts the multiplexed signal into an optical signal having a wavelength different from that of the operating signal, thereby making the accommodation mode settable for each channel in an independent manner.

Abstract: In one embodiment, notifications of upcoming maintenance activities are provided by network devices, such as to allow packet switching or other optical layer client devices to reroute traffic prior to the occurrence of the traffic affecting event. For example, one such network device includes optical interfaces for coupling with fibers for transporting information using dense wavelength-division multiplexing (DWDM); DWDM switching equipment for cross-connecting wavelengths of the fibers; and a controller configured to inform packet switching or other optical layer client devices whose traffic would be affected by an upcoming event that would disrupt communication on one or more wavelengths on one or more fibers so that the packet switching or other optical layer client devices can reroute traffic that would otherwise go over said one or more wavelengths onto a different path in a network prior to said disruption.

Abstract: A wave division multiplexing (WDM) system is disclosed which accommodates shifts in the resonant frequency of optical modulators by using at least two carriers per optical communications channel and at least two resonant modulator circuits respectively associated with the carriers within each optical modulator. A first resonant modulator circuit resonates with a first carrier and a second resonates with a second carrier when there is a shift in resonance frequency of the at least two resonant optical modulator circuits. A switch circuit controls which carrier is being modulated by its respective resonant modulator circuit.

Abstract: The present invention embraces an optical wavelength division multiplex (WDM) transmission system, especially a WDM passive optical network, typically including a central node having a first and a second WDM port and a remote node having a first and a second WDM port and a plurality of channel ports, the central node first WDM port being connected to the remote node first WDM port via a bidirectional single-fiber optical working path and the central node second WDM port being connected to the remote node second WDM port via a single-fiber bidirectional optical protection path, and a group of basic optical node units (ONU's) each of which is connected to a respective remote node channel port via a bidirectional optical ONU path, each ONU including an optical receiver for receiving a downstream optical channel signal and an optical tunable transmitter for creating an upstream channel signal.

Abstract: Method and apparatus for operating for operating an optical network including a shared laser array are disclosed. An example apparatus includes include a first plurality of N lasers. Each laser of the first plurality of N lasers is configured to output a respective optical seed signal having a respective wavelength. The example apparatus further includes a first optical coupler coupled with the first plurality of N lasers. In the example embodiment, the first optical coupler is configured to multiplex the respective optical seed signals of the first plurality of N lasers onto a plurality of N optical fibers. In this example, each optical fiber of first plurality of N optical fibers transmits each of the respective optical seed signals produced by the plurality of N lasers to a respective distribution node for distribution to N respective optical network units, where the optical network units use the optical seed signals to seed respective optical transmitters located at the N optical network units.

Abstract: A system and method for fault recovery in a branched optical network. In response to a fault, power distribution in channels on recovering digital line segments is adjusted to minimize a merit function based on one or more system parameters.

Abstract: An optical network system includes a first node that converts input signals of n systems into optical signals having wavelengths different for each of the systems and wavelength-multiplexes and transmits the optical signals and a second node that selects signals of n systems from the wavelength-multiplexed signals and outputs the signals. The first node includes an optical coupler that divides the input signals into operating system signals and redundant signals, TPNDs that convert the operating systems into optical signals, an optical switch that selects standby system signals from the redundant signals, and a TPND that converts the standby system signals into optical signals in a storage mode corresponding to a type of the standby system signals.

Abstract: The present invention does not require control and path switching by terminal station equipment and prevents the deterioration of signal quality when a cable failure occurs. A wavelength diverging device connected with three or more stations monitors an uplink signal received from each station, and when detecting the absence of an uplink signal received from any station, outputs dummy light instead of the absent signal, performs multiplexing/de-multiplexing for the dummy light and an uplink signal received from a station excluding said any station, and outputs the multiplexed/de-multiplexed signal. All of said processes are performed within the wavelength diverging device.

Abstract: A system for data communication networks and a method for data communication networks, the data communication network including a label switch path, the method comprising the steps of providing a list including a plurality of entries, wherein each entry includes a wavelength that can be used by the label switch path for recovery procedures.

Abstract: A method and system for protecting integrated optoelectronic devices are disclosed. The method includes (1) providing standby light source links of fixed wavelength and their corresponding standby data channel in a transmitting-end integrated optoelectronic device; (2) detecting whether there is failure in each active light source link in the transmitting-end integrated optoelectronic device; and (3) selecting a standby light source link having a fixed wavelength and its corresponding standby data channel for accomplishing service transmission of failed active light source link and its corresponding active data channel when detecting failure of an active light source link. The system includes a transmitting-end integrated optoelectronic device and a receiving-end integrated optoelectronic device.

Abstract: The present invention discloses a method and a system for shared protection in WDM loop network. The WDM loop network comprises at least one node, and each node is divided into a multiplexing segment layer, a channel layer and a sub-wavelength layer. The method for shared protection comprises the following steps: A, the multiplexing segment layer, the channel layer and the sub-wavelength layer of each node are detected respectively; B, the detection point generates fault information when at least one of the multiplexing segment layer, the channel layer and the sub-wavelength layer goes wrong; and a controller of each node, according to the fault information, determines the protection control state of the present node and notifies the respective executor; wherein the protection control state includes service adding, service passing through, and service dropping; C, the executor of each node controls the corresponding node to switch to the protection control state determined in step B.

Abstract: A storage device stores information regarding a channel from which an optical transmission apparatus at a subsequent stage drops a signal light. A processor determines that switching from second channel transmission using a larger number of channels than a first number of channels to first channel transmission is performed, and controls an attenuation amount, when performing the first channel transmission using the first number of channels, by referring to the storage device according to the determination and making the attenuation amount in a no-signal channel larger than a determine value if the no-signal channel whose wavelength is within a determined range from the wavelength of the signal light channel for the first channel transmission is a channel from which the optical transmission apparatus at the subsequent stage drops a signal light, so as to transmit an amplified spontaneous emission light along the no-signal channel.

Abstract: An optical add-drop multiplexer branching unit and its control method are provided according to the present disclosure. The optical add-drop multiplexer branching unit includes: four wavelength division multiplexers WDM1 to WDM4 and a first optical switch module, where WDM1 to WDM4 are configured to divide or combine wavelengths of signals; the first optical switch module is configured to control connection and disconnection of signals that leave and enter the four wavelength division multiplexers; the first optical switch module includes port 1 to port 4; the ports are connected with input ports or output ports of WDM1 to WDM4, respectively; states of internal connection between the ports include state 1 and state 2. The OADM BU in the foregoing solutions is characterized by simple structure, easy control, and high capability of disaster recovery.

Abstract: A multi-wavelength optical transmission system includes a plurality of primary optical transmitters, each being configured to provide directly modulated analog optical signals at non-uniformly spaced apart wavelengths. An optical multiplexer having a plurality of optical input ports receives the analog optical signals from each of the plurality of primary optical transmitters and provides a wavelength division multiplexed signal over an optical fiber coupled at an output thereof. A spare optical transmitter is coupled to an input port of the optical multiplexer and, in response to detecting failure of a failed one of the plurality of primary optical transmitters, is tuned to provide a directly modulated analog optical signal at a spare wavelength that is selected as to be non-uniformly spaced relative to at least some of the non-uniformly spaced apart wavelengths according to tuning data.

Abstract: A method for realizing service protection in the automatically switched optical network includes following steps: after any defect occurs on the working paths that carry the service, the first node and the last node of the working paths sends the requests to restore the paths setup in opposite directions, respectively; at least one intermediate node in the restoration path establishes a connection according to the restoration path setup request, and forwards the restoration path setup request hop by hop, until the setup of the recovering path is finished; the service is switched from the working paths to the restoration paths. A system for realizing service protection and a node device in an ASON is also provided. The paths restoration process can be faster obviously using this invention, and the restoration time can be shortened, and the work efficiency and reliability can be improved, and the service can be ensured to be restored.

Abstract: Various example embodiments are disclosed. According to an example embodiment, a method may include determining that a transmission of a data signal over a path of a wavelength division multiplexed (WDM) optical network using a group of optical subcarriers is not optically feasible; determining that the transmission of the data signal over the path using a subset of the group of optical subcarriers is optically feasible; activating subcarriers for the subset of optical carriers while deactivating one or more optical subcarriers of the group, at least one deactivated subcarrier provided between at least two activated subcarriers of the group; and transmitting the data signal over at least a portion of the path using the activated subcarriers of the group.

Abstract: The present invention discloses a passive optical network (PON) protection method, a switchover control device, and a PON protection system. In embodiments of the present invention, a protection optical line terminal (OLT) is connected to optical links of at least two working OLTs through the switchover control device; when a working OLT or working optical link fails, the switchover control device replaces the working OLT through the protection optical link, thus ensuring smooth communication. In addition, by using the networking mode of multiple working OLTs and one protection OLT, the embodiments of the present invention greatly saves the networking cost and facilitates the application of the PON technology.

Abstract: The present invention embraces an optical wavelength division multiplex (WDM) transmission system, especially a WDM passive optical network, typically including a central node having a first and a second WDM port and a remote node having a first and a second WDM port and a plurality of channel ports, the central node first WDM port being connected to the remote node first WDM port via a bidirectional single-fiber optical working path and the central node second WDM port being connected to the remote node second WDM port via a single-fiber bidirectional optical protection path, and a group of basic optical node units (ONU's) each of which is connected to a respective remote node channel port via a bidirectional optical ONU path, each ONU including an optical receiver for receiving a downstream optical channel signal and an optical tunable transmitter for creating an upstream channel signal.

Abstract: An optical transmission device includes a wavelength multiplexing/demultiplexing unit, a plurality of transponders, an optical switch unit and a controller. The controller includes a table in which a plurality of items at least including priority order, a transmission label, a receiving label and a receiving label expected value correspond to the respective transponders. And the controller rewrites the transmission label of the transponder corresponding to the client device of the lower priority order than the priority order of the client device connected to the transponder of the irregular input, upon the optical signal provided by the wavelength multiplexing/demultiplexing unit to one of the transponders being irregular, and controls the label-changed transponder for which the transmission label has been rewritten so that the label-changed transponder provides the wavelength multiplexing/demultiplexing unit with the optical signal including the rewritten transmission label.

Abstract: The present invention discloses a passive optical network (PON) protection method, a switchover control device, and a PON protection system. In embodiments of the present invention, a protection optical line terminal (OLT) is connected to optical links of at least two working OLTs through the switchover control device; when a working OLT or working optical link fails, the switchover control device replaces the working OLT through the protection optical link, thus ensuring smooth communication. In addition, by using the networking mode of multiple working OLTs and one protection OLT, the embodiments of the present invention greatly saves the networking cost and facilitates the application of the PON technology.

Abstract: An optical communication system including optical transmission systems each includes a transmission processing unit and a receiving processing unit, wherein the transmission processing unit includes an optical transmission unit that converts electric signals into optical signals, an auxiliary optical transmission unit that converts a part of the electric signals into an optical signal having a wavelength other than wavelengths of the optical signals generated by the optical transmission unit, and outputs the generated optical signal to a different transmission processing unit, and a wavelength multiplexing unit, and the receiving processing unit includes a wavelength demultiplexing unit, an optical receiving unit that converts the optical signals having the wavelengths of the optical signals generated by the optical transmission unit into electric signals, respectively, and an auxiliary optical receiving unit that converts the optical signal having the wavelength of the optical signal generated by the auxilia

Abstract: Schemes are provided for starting up optical transmission links where, after a link interruption, endpoints switch into a startup mode original detection state, and a query-transmit pulse goes out at both end points at given time intervals. In a “TRANSMITTED” handshake mode, in a loop to be passed through n times, and at least once, after the transmission of a transmit pulse, it is detected whether a received pulse is received within a given time span. If no received pulse is received, then the mode is ended and the system is returned to the original detection state. If a received pulse is received, it is answered with another transmit pulse. After the last transmit pulse, if another received pulse occurs within a given time span, the link is activated. If not, the “TRANSMITTED” handshake mode ends and the system enters the original detection state.