Multiple receivers are comprised in a flexible coherent transceiver of a multi-span optical fiber network. Each of the multiple receivers is operative to handle communications on a respective channel. The multiple receivers measure optical characteristics. For each of the multiple receivers, the optical characteristics include optical nonlinear interactions on the respective channel, the optical nonlinear interactions being at least partially dependent from one span to another span. An optical power of a signal on each of the multiple channels is adjusted as a function of the optical characteristics.

Systems and methods for path computation in an optical network include obtaining optical layer characteristics related to one or more optical paths in the optical network based in part on performance measurements in the optical network; responsive to service establishment or service restoration, determining a path from source to destination based on utilizing the optical layer characteristics to confirm physical validity of the path; and provisioning a service on the determined path from the source to the destination in the optical network.

At a first optical node of an optical communications system, during a signal initialization phase, a first optical pattern is received that includes a prefix indicating a beginning of a signal, a first word, and a first working signal for verifying stability of a connection between the first optical node and a second optical node of the optical communications system. A second optical pattern is transmitted that includes the prefix, a second word different from the first word, and the first working signal. A third optical pattern including the prefix, the first word, and a second working signal is received. Based on determining that a duration of the second working signal is greater than a duration of the first working signal plus a predetermined time, the first optical node determines that the second optical node is an adjacent node of the first optical node.

A system and method for performing an in-service optical time domain reflectometry test, an in-service insertion loss test, and an in-service optical frequency domain reflectometry test using a same wavelength as the network communications for point-to-point or point-to-multipoint optical fiber networks while maintaining continuity of network communications are disclosed.

An optical line terminal (OLT) coupled to a plurality of optical network units (ONUs) through a passive optical network (PON). The OLT includes a transceiver configured to communicate via a management channel of a communication network with a plurality of OLTs. The communication includes sending or receiving a notification, wherein the notification includes the following: a source OLT identifier associated with a source OLT sending the notification, wherein the source OLT is configured to communicate over a first channel at a first wavelength of the PON; a destination OLT identifier associated with a destination OLT receiving the notification, wherein the destination OLT is configured to communicate over a second channel at a second wavelength of the PON; and an ONU identifier associated with a first ONU associated with the notification.

An optical modulator combines and inputs a signal light propagating through the optical network and a control light having information concerning the optical network to a nonlinear optical medium. The optical modulator modulates the signal light according to changes in intensity of the control light, in the nonlinear optical medium.

An apparatus includes a memory and a processor operatively coupled to the memory. The processor is configured to partition a set of ports of an optical multiplexer into a set of port groups including a first port group having a first set of ports and a second port group having a second set of ports mutually exclusive from the first set of ports. The processor is configured to associate the first port group with a first router and associate the second port group with a second router. When the optical multiplexer is operatively coupled to the first router and the second router, the first router is operatively coupled to the optical multiplexer via the first set of ports and not the second set of ports, and the second router is operatively coupled to the optical multiplexer via the second set of ports and not the first set of ports.

A transmission system includes a plurality of nodes in which respective adjacent nodes are coupled by a first kind of optical fiber compatible with light in a first wavelength band or a second kind of optical fiber compatible with light in a second wavelength band, wherein each of the plurality of nodes includes a transmitting node that generates a wavelength-multiplexed optical signal in the first wavelength band by carrying out wavelength multiplexing of a plurality of optical signals and transmits the wavelength-multiplexed optical signal, a receiving node that demultiplexes the plurality of optical signals from the wavelength-multiplexed optical signal and receives the plurality of optical signals, and one or more relay nodes that relay the wavelength-multiplexed optical signal from the transmitting node to the receiving node through the first kind or the second kind of optical fiber.

Provided is a signal loopback circuit which, in order to loop back a monitoring signal in a relay device for relaying optical signals of a plurality of wavelength bands, connects between a channel of first direction and a channel of second direction through which an optical signal of first wavelength band and an optical signal of second wavelength band are transmitted, wherein the signal loopback circuit is provided with a first coupler for branching the optical signal on the channel of first direction, a first filter for extracting at least one of a monitoring signal of first wavelength band and a monitoring signal of second wavelength band that are used in the channel of first direction from the optical signal branched by the first coupler, and a second coupler for causing the monitoring signal extracted by the first filter to be joined to the channel of the second direction.

An optical transmission apparatus for transmitting a main signal, the optical transmission apparatus being arranged on an optical transmission line, the optical transmission apparatus includes a first processor configured to perform alarm supervision and signal control of the optical transmission apparatus; a second processor configured to perform the alarm supervision and the signal control of the optical transmission apparatus during a period when the first processor is in a stopped state; inter-apparatus transmitter and receivers configured to transmit and receive a signal including control information for the alarm supervision between the first and second processors and another optical transmission apparatus facing the optical transmission apparatus; and a multiplexer and demultiplexer configured to couple and split the signal for the main signal optically communicated with the another optical transmission apparatus.