The embodiments disclosed herein provide fast recovery of a network signal path by, in the event of a failure or unacceptable degradation in a signal in the original network path, diverting the optical signal passing through the network to a preselected bypass optical path which is maintained in a warm or operational state. The optical elements on the bypass optical path are available network resources which may, during part or all of the time the bypass path is designated for a node in the primary optical path, be in use to transmit other optical signals in the network. By maintaining the resources in the designated bypass path in a warm or operating state, fast rerouting and recovery of an interrupted signal is possible.

A method generates, from an input data stream, multiple lanes of a physical coding sublayer (PCS) signal. The method converts the data stream to a sequence of bit blocks, and periodically inserts into the sequence of bit blocks an alignment marker (AM) group including multiple individual alignment markers for respective ones of the multiple lanes. The method adds security protection to each bit block according to a security protocol to produce a sequence of protected bit blocks, and modifies each AM group with security information to be used by the security protocol to remove the security protection added to the sequence of protected bit blocks. The method applies forward error correction to the sequence of protected bit blocks and the modified AM groups to produce forward error correction codewords, and produces the multiple lanes from the codewords. The method transmits the multiple lanes over an optical link.

A transmission apparatus includes a first communication unit, a second communication unit, a detection unit, a control unit, and a selection unit. The first communication unit uses a first path for communication, when electric power is supplied. The second communication unit uses a second path for communication, when electric power is supplied. The detection unit detects a fault predictive sign. The control unit supplies no electric power to the second communication unit when the detection unit does not detect the fault predictive sign. The control unit starts supplying electric power to the second communication unit and performs normality confirmation of the second path when the detection unit detects the fault predictive sign, before switching from the first path to the second path. The selection unit selects and outputs, when the first communication unit and the second communication unit have received signals, either the signal received by the first communication unit or the signal received by the second communication unit.

The present invention discloses a passive optical network communications method, apparatus and system. The method includes: receiving, by an optical network unit, a first message sent by an optical line terminal, where the first message carries backup wavelength channel ID information; switching, by the optical network unit, following the optical network unit detects a fault, an operating wavelength channel of the optical network unit to a backup wavelength channel identified by the backup wavelength channel ID information; and performing, by the optical network unit, data communication over the switched-to backup wavelength channel. In this way, fast protection switching of a passive optical network system is implemented and reliability of the system is improved.

A method of implementing a stretched single optical communication span includes receiving one or more optical signals from an optical fiber span having high loss; adding a pilot signal to the one or more optical signals, subsequent to the receiving; and amplifying the one or more optical signals and the pilot signal with a pre-amplifier that is an Erbium Doped Fiber Amplifier (EDFA). Advantageously, the stretched single span operates below a Hazard 1M environment. A node in a stretched single optical communication span includes an optical multiplexer connected to an optical fiber span having high and a pilot signal, and configured to output a combination of one or more optical signals from the optical fiber span and the pilot signal; and a pre-amplifier that is an EDFA configured to receive the output of the optical multiplexer and provide amplification of the one or more optical signals and the pilot signal.

This disclosure describes devices and methods related to multiplexing optical data signals. A method may be disclosed for multiplexing one or more optical data signals. The method may comprise receiving, by a dense wave division multiplexer (DWDM), one or more optical data signals. The method may comprise combining, by the DWDM, the one or more optical data signals. The method may comprise outputting, by the DWDM, the combined one or more optical data signals to one or more wave division multiplexer (WDM). The method may comprise combining, by the one or more WDM, the combined one or more optical data signals and one or more second optical data signals, and outputting an egress optical data signal comprising the combined one or more optical data signals and one or more second optical data signals.

An apparatus includes a first input port, a first switch, and a second switch. The first switch and the second input port are in optical communication with the first input port. The apparatus also includes a second input port, a third switch, and a fourth switch. The third switch and the fourth switch are in optical communication with the second input port. Each switch is switchable between a first state to pass optical signals and a second state to block optical signals. The apparatus also includes a first combiner in optical communication with the first input port via the first switch and the second input port via the third switch. The apparatus also includes a second combiner in optical communication with the first input port via the second switch and the second input port via the fourth switch.

An apparatus includes a first reconfigurable optical add/drop multiplexer (ROADM) to receive a first optical signal and a second ROADM to receive a second optical signal. The apparatus also includes a reconfigurable optical switch that includes a first switch, switchable between a first state and a second state, to transmit the first optical signal at the first state and block the first optical signal at the second state. The reconfigurable optical switch also includes a second switch, switchable between the first state and the second state, to transmit the second optical signal at the first state and block the second optical signal at the second state. The reconfigurable optical switch also includes an output port to transmit an output signal that is a sum of possible optical signals transmitted through the first switch and the second switch.

A method generates, from an input data stream, multiple lanes of a physical coding sublayer (PCS) signal. The method converts the data stream to a sequence of bit blocks, and periodically inserts into the sequence of bit blocks an alignment marker (AM) group including multiple individual alignment markers for respective ones of the multiple lanes. The method adds security protection to each bit block according to a security protocol to produce a sequence of protected bit blocks, and modifies each AM group with security information to be used by the security protocol to remove the security protection added to the sequence of protected bit blocks. The method applies forward error correction to the sequence of protected bit blocks and the modified AM groups to produce forward error correction codewords, and produces the multiple lanes from the codewords. The method transmits the multiple lanes over an optical link.

The present invention discloses a passive optical network communications method, apparatus and system. The method includes: receiving, by an optical network unit, a first message sent by an optical line terminal, where the first message carries backup wavelength channel ID information; switching, by the optical network unit when the optical network unit detects a fault, an operating wavelength channel of the optical network unit to a backup wavelength channel identified by the backup wavelength channel ID information; and performing, by the optical network unit, data communication over the switched-to backup wavelength channel. In this way, fast protection switching of a passive optical network system is implemented and reliability of the system is improved.