An optical line terminal is operable in a passive optical network. The optical line terminal includes a chassis. A plurality of optical subsystems are disposed within the chassis. Each optical subsystem is operable to generate optical signals for delivery to a port. Each optical subsystem includes one or more optical switches. When a fault condition is detected at a first optical subsystem preventing the delivery of first optical signals generated by the first optical subsystem to the port of the first optical subsystem, the optical switches switch to deliver second downstream optical signals generated by a second optical subsystem to the port of the first optical subsystem.

An optical source switching apparatus including first optical sources, an optical cross-connect device, second optical sources, and a first coupler. The optical cross-connect device is connected to the first optical sources and the first coupler, and the first coupler is connected to the second optical source; both the first optical source and the second optical source are configured to output continuous optical energy, and the optical cross-connect device is configured to enable optical energy output by at least one of the first optical sources to enter the first coupler when at least one of the second optical sources fails; and the first coupler is configured to implement beam splitting of the optical energy output by the first optical source or the second optical source.

A fault-tolerant quantum computer using topological codes such as surface codes can have an architecture that reduces the amount of idle volume generated. The architecture can include qubit modules that generate surface code patches for different qubits and a network of interconnections between different qubit modules. The interconnections can include port connections that selectably enable coupling of boundaries of surface code patches generated in different qubit modules and/or quickswap connections that selectably enable transferring the state of a surface code patch from one qubit module to another. Port and/or quickswap connections can be made between a subset of qubit modules. For instance port connections can connect a given qubit module to other qubit modules within a fixed range. Quickswap connections can provide a log-tree network of direct connections between qubit modules.

Systems and methods implemented by an all-optical switch configured to switch signals optically in an optical network include receiving and processing call information from a messaging/signaling session, wherein the call information relates to one or more calls on ports in the all-optical switch; and configuring the ports in the all-optical switch in the network based on the processed call information. The call information can include detection of one of a fault and a lockout on the one or more ports and an indication of faults in the optical network. One of a control plane and an SDN controller can be connected to the all-optical switch via the messaging/signaling session.

Provided is a linear automatic protection switching (APS) apparatus and method that minimizes a data loss in an optical transport network (OTN) system, the apparatus and method that may maintain time synchronization by transmitting/receiving time synchronization signals between APS apparatuses of a working path and a redundant path, and transmitting/receiving time synchronization signals between local and remote APS apparatuses.

A transmission device for which a work path is established in a first degree and a protection path is established in a second degree includes: a switch equipped with a plurality of optical ports; an optical signal generator, optically connected to a first optical port, and configured to generate an optical signal that is transmitted through the work path; and a monitor light generator, optically connected to a second optical port, and configured to generate monitor light by using a wavelength tunable light source. The monitor light generator controls a wavelength of the monitor light to be substantially the same as a wavelength of the optical signal. The switch guides the optical signal that arrives at the first optical port toward the first degree and guides the monitor light that arrives at the second optical port toward the second degree.

A fault-tolerant quantum computer using topological codes such as surface codes can have an architecture that reduces the amount of idle volume generated. The architecture can include qubit modules that generate surface code patches for different qubits and a network of interconnections between different qubit modules. The interconnections can include port connections that selectably enable coupling of boundaries of surface code patches generated in different qubit modules and/or quickswap connections that selectably enable transferring the state of a surface code patch from one qubit module to another. Port and/or quickswap connections can be made between a subset of qubit modules. For instance port connections can connect a given qubit module to other qubit modules within a fixed range. Quickswap connections can provide a log-tree network of direct connections between qubit modules.

A method to avoid sympathetic switches in path switching protection due to client protection switching includes monitoring a drop side Tandem Connection Monitoring (TCM) entity and a line side TCM entity for a connection, wherein the drop side TCM is provisioned between a drop port of the node and a second drop port of a corresponding node, and wherein the line side TCM entity is provisioned between a plurality of line ports of the node and a second plurality of line ports of the corresponding node; responsive to detecting defects in both the drop side TCM entity and the line side TCM entity on a working line, implementing path protection switching of the working line; and, responsive to detecting defects only in the drop side TCM entity, implementing path protection switching of the working line responsive to persistence of the defects.

Systems and methods implemented by an all-optical switch configured to switch signals optically in an optical network include receiving and processing call information from a messaging/signaling session, wherein the call information relates to one or more calls on ports in the all-optical switch; and configuring the ports in the all-optical switch in the network based on the processed call information. The call information can include detection of one of a fault and a lockout on the one or more ports and an indication of faults in the optical network. One of a control plane and an SDN controller can be connected to the all-optical switch via the messaging/signaling session.

Systems and methods for controlling an optical switch via one of a control plane and Software Defined Networking (SDN) include associating one or more managed endpoints with one or more line ports of an optical switch; receiving state information for the one or more managed endpoints over a session associated with one of the control plane and the SDN; and controlling switching of the one or more line ports based on the state information for the one or more managed endpoints. The optical switch is an all-optical device which does not have access to digital signal quality information of associated signals.