An optical branching/coupling device includes: a first optical branching unit that splits first light with a first and a second wavelength, and outputs second light and third light; a wavelength selector that receives the second light, receives fourth light with a third wavelength, output fifth and sixth light, one of the fifth light and the sixth light including an optical signal of the first wavelength of the second light and including the fourth light, and the other including an optical signal of the second wavelength; a first light switch that receives the fifth light and the sixth light, output one of the fifth light and the sixth light as seventh light, and output the other as eighth light; and a second light switch that receives the third light, receives the eighth light, and outputs the third or the eighth light that have been input as ninth light.

Provided are a junction device and an undersea cable system capable of saving a branch line when a problem involving ground fault occurs in a power feed line on a branch station side. This junction device is inserted into a power feed line and a transmission line connecting first and second trunk stations and a branch station, and includes a switching means for controlling a switch so as to connect the transmission line between the branch station and the first or second trunk station when a current detection means detects that there is no longer current flowing through the power feed line between a junction unit and the branch station and when a first optical signal detection means detects an optical signal in the transmission line connecting the junction unit and the branch station.

Provided are a junction device and an undersea cable system capable of saving a branch line when a problem involving ground fault occurs in a power feed line on a branch station side. This junction device is inserted into a power feed line and a transmission line connecting first and second trunk stations and a branch station, and includes a switching means for controlling a switch so as to connect the transmission line between the branch station and the first or second trunk station when a current detection means detects that there is no longer current flowing through the power feed line between a junction unit and the branch station and when a first optical signal detection means detects an optical signal in the transmission line connecting the junction unit and the branch station.

This application provides an example light source switching apparatus. The apparatus includes first and second multi-mode interference (MMI) couplers, and a phase modulator. The first MMI coupler includes four ports, where first and second ports are located on one side, and third and fourth ports are located on the other side. The second MMI coupler includes three ports, where fifth and sixth ports are located on one side, and a seventh port is located on the other side. The first and the second ports connect to the fifth and the sixth ports, respectively, to form two connections. The phase modulator is disposed on one of the two connections, and the seventh port connects to an optical modulator. Both the third and the fourth ports connect to a light source emitting continuous light, and the phase modulator selects one of the two light sources for output from the seventh port.

Various embodiments for configurable memory storage systems are disclosed. The configurable memory storages selectively choose an operational voltage signal from among multiple voltage signals to dynamically control various operational parameters. For example, the configurable memory storages selectively choose a maximum voltage signal from among the multiple voltage signals to maximize read/write speed. As another example, the configurable memory storages selectively choose a minimum voltage signal from among the multiple voltage signals to minimize power consumption.

Various embodiments for configurable memory storage systems are disclosed. The configurable memory storages selectively choose an operational voltage signal from among multiple voltage signals to dynamically control various operational parameters. For example, the configurable memory storages selectively choose a maximum voltage signal from among the multiple voltage signals to maximize read/write speed. As another example, the configurable memory storages selectively choose a minimum voltage signal from among the multiple voltage signals to minimize power consumption.

An OLT includes a storage unit that stores management information indicating that a first address has been assigned to a client device that connects to an ONU as an operational system and an ONU as a standby system, a detection unit that detects occurrence of a failure to the ONU, a communication control unit that, connects to the ONU when the occurrence of the failure to the first slave station device is detected and controls communication performed by the client device so that the client device connects to the Internet via the ONU and the OLT, and a monitoring unit that monitors unauthorized use of the first address based on the management information both when the client device connects to the Internet via the ONU and the OLT and when the client device connects to the Internet via the ONU and the OLT.

An OLT includes a storage unit that stores management information indicating that a first address has been assigned to a client device that connects to an ONU as an operational system and an ONU as a standby system, a detection unit that detects occurrence of a failure to the ONU, a communication control unit that, connects to the ONU when the occurrence of the failure to the first slave station device is detected and controls communication performed by the client device so that the client device connects to the Internet via the ONU and the OLT, and a monitoring unit that monitors unauthorized use of the first address based on the management information both when the client device connects to the Internet via the ONU and the OLT and when the client device connects to the Internet via the ONU and the OLT.

The purpose of the present invention is to provide an optical/RF wireless hybrid communication system and a control method capable of solving the instability of link conditions of an RF wireless link and an optical wireless link. In the optical/RF wireless hybrid communication system and the control method according to the present invention, links for data transmission are not limited to one of an RF wireless link and an optical wireless link, the quality of link conditions is determined from signal quality received through channels of both the RF wireless link and the optical wireless link, and the distribution of data to be transmitted through the respective links is determined on the basis of the determination result. Thus, the links can be flexibly switched depending on the transmission conditions such as disturbance.

The purpose of the present invention is to provide an optical/RF wireless hybrid communication system and a control method capable of solving the instability of link conditions of an RF wireless link and an optical wireless link. In the optical/RF wireless hybrid communication system and the control method according to the present invention, links for data transmission are not limited to one of an RF wireless link and an optical wireless link, the quality of link conditions is determined from signal quality received through channels of both the RF wireless link and the optical wireless link, and the distribution of data to be transmitted through the respective links is determined on the basis of the determination result. Thus, the links can be flexibly switched depending on the transmission conditions such as disturbance.