A branching unit is provided for interconnecting at least three undersea optical
transmission cables. The branching unit includes first, second and third ports
for receiving first, second and third undersea optical transmission cables, respectively.
The first and second cables each include an electrical power conductor and a plurality
of first optical fibers. The third cable is electrically unpowered and includes
at least one drop optical fiber and at least one add optical fiber. An electrical
power conductor segment is provided for electrically coupling the conductor in
the first cable received in the first port to the conductor in the second cable
received in the second port. A first optical fiber segment optically couples a
first of the plurality of first optical fibers in one of the first or second cables
to the drop optical fiber of the third cable. A second optical fiber segment optically
couples a second of the plurality of first optical fibers in one of the first and
second cables to the add optical fiber of the third cable. First and second optical
amplifiers are located along the first and second optical fiber segments, respectively
so that the first optical amplifier provides optical gain to traffic being dropped
on the drop optical fiber of the third cable and the second optical amplifier provides
optical gain to traffic being added on the add optical fiber of the third cable.
At least one electrically conductive path is provided for supplying electrical
energy from at least one of the electrical power conductors to each of the optical amplifiers.