Systems and methods for monitoring an Optical Multiplex Section of a communication network are provided. A method, according to one implementation, includes the step of obtaining parameters related to optical signals traversing an Optical Multiplex Section (OMS) of a communication network. The OMS, in this example, includes multiple fiber spans defining a primary path and one or more protection paths. The method further includes the step of using the obtained parameters to determine a Signal-to-Noise Ratio (SNR) value associated with optical signals transmitted over the primary path. In response to determining that the SNR value falls below a predetermined threshold, the method includes the step of performing a switching action to enable transmission of optical signals over one of the one or more protection paths.

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.

The present invention includes novel techniques, apparatus, and systems for optical WDM communications. Tunable lasers are employed to generate respective subcarrier frequencies which represent subchannels of an ITU channel to which client signals can be mapped. In one embodiment, subchannels are polarization interleaved to reduce crosstalk. In another embodiment, polarization multiplexing is used to increase the spectral density. Client circuits can be divided and combined with one another before being mapped, independent of one another, to individual subchannels within and across ITU channels. A crosspoint switch can be used to control the client to subchannel mapping, thereby enabling subchannel protection switching and hitless wavelength switching. Network architectures and subchannel transponders, muxponders and crossponders are disclosed, and techniques are employed (at the subchannel level/layer), to facilitate the desired optical routing, switching, concatenation and protection of the client circuits mapped to these subchannels across the nodes of a WDM network.

An optical communication system of the present invention switches a communication wavelength from a current communication wavelength to a auxiliary communication wavelength when an abnormality occurs in a communication wavelength between a station-side device and any one of a plurality of subscriber devices. Further, this optical communication system switches a communication wavelength used for communication between the subscriber device and the station-side device that perform communication using the auxiliary communication wavelength from the auxiliary communication wavelength back to the current communication wavelength when communication is recovered from an abnormality in the current communication wavelength.

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.

A transmission apparatus includes: a storage unit to store a table in which a wavelength terminated by each of transmission apparatuses is associated with each of the transmission apparatuses; a transmission unit to transmit a message including failure information to other transmission apparatus when a failure occurs; a switch controller to determine whether its own transmission apparatus is a last transmission apparatus that terminates the wavelength among transmission apparatuses that are present on a path up to a link where the failure, based on the table, when receiving the message from other transmission apparatus, and to perform a control of switching a transmission direction of a signal having the wavelength when the switch controller determines that its own transmission apparatus is the last transmission apparatus to terminate the wavelength; and a switch to switch a transmission direction of the signal for each wavelength under a control of the switch controller.

An optical transmission device includes: a plurality of optical transceivers; a wavelength selective switch; and a controller configured to control the plurality of optical transceivers and the wavelength selective switch. Each of the optical transceivers includes a wavelength tunable light source. The controller controls a wavelength of a wavelength tunable light source of a selected optical transceiver according to a wavelength of an optical signal received by the destination remote device. The controller controls the wavelength selective switch so as to generate the WDM optical signal from a plurality of optical signals generated by the plurality of optical transceivers, and to guide the plurality of optical signals received from the plurality of remote devices to the plurality of optical transceivers according to wavelengths of the received plurality of optical signals.

The present invention includes novel techniques, apparatus, and systems for optical WDM communications. Tunable lasers are employed to generate respective subcarrier frequencies which represent subchannels of an ITU channel to which client signals can be mapped. In one embodiment, subchannels are polarization interleaved to reduce crosstalk. In another embodiment, polarization multiplexing is used to increase the spectral density. Client circuits can be divided and combined with one another before being mapped, independent of one another, to individual subchannels within and across ITU channels. A crosspoint switch can be used to control the client to subchannel mapping, thereby enabling subchannel protection switching and hitless wavelength switching. Network architectures and subchannel transponders, muxponders and crossponders are disclosed, and techniques are employed (at the subchannel level/layer), to facilitate the desired optical routing, switching, concatenation and protection of the client circuits mapped to these subchannels across the nodes of a WDM network.

The present invention includes novel techniques, apparatus, and systems for optical WDM communications. Tunable lasers are employed to generate subcarrier frequencies representing subchannels of an ITU channel to which client signals can be mapped. Client circuits can be divided and combined before being mapped, independent of one another, to individual subchannels within and across ITU channels. Subchannels may be independently routed to a single subchannel receiver filter, such that each subchannel detected at the receiver may come from a different source location. Network architectures and subchannel transponders, muxponders and crossponders are disclosed, and techniques are employed (at the subchannel level/layer), to facilitate the desired optical routing, switching, concatenation and protection of client circuits mapped to these subchannels across the nodes of a WDM network. Subchannel hopping may also be used to increase the optical network security.

A fiber optic network has alarmed fiber optic lines in the cables connecting a secured junction box to plural user lock boxes. An outgoing alarm line and return alarm line in each cable connect the junction box to each user box. The outgoing alarm line is looped to the return alarm line inside the user lock box. The return alarm line is looped to the outgoing alarm line of a different cable inside the junction box to interconnect a plurality of alarm lines passing through a plurality of user boxes. A detector detects an alarm signal in the connected alarm lines to trigger an intrusion alarm.