Abstract: An optical submarine branching unit for branching a trunk cable into first and second branch cables, including a pressure housing having a cylinder and first and second covers, a branching circuit unit accommodated in the pressure housing, a first feed through assembly mounted to the first cover so as to extend therethrough, for introducing optical fibers of the trunk cable into the pressure housing, and second and third feed through assemblies mounted to the second cover so as to extend therethrough, for introducing optical fibers of the first and second branch cables into the pressure housing, respectively. The branching circuit unit has a feeding unit and an optical circuit unit completely separated from the feeding unit. Each feed through assembly includes a sleeve and a pin inserted in the sleeve. The pin has a plurality of bosses each having a plurality of axial grooves. Multiple layers of optical fibers are received in each axial groove and extend along the pin.

Abstract: A circuit unit including heating components is accommodated in a space defined by a cylindrical metal case and a pair of case end plates closing the opposite ends of the metal case. The metal case is accommodated in an insulated space defined by a PE cylinder formed of insulating resin such as polyethylene and a pair of PE end plates closing the opposite ends of the PE cylinder. The PE cylinder is accommodated in a pressure-resistant housing through a first radiating/cushioning member. A radiating disk biased by a second radiating/cushioning member is kept in pressure contact with each PE end plate kept in close contact with the corresponding case end plate.

Abstract: An optical repeater having a first optical fiber extending from an input optical fiber cable, a light amplifying medium connected to the first optical fiber, a pumping light source for outputting pumping light, an optical coupling module for introducing the pumping light into the light amplifying medium, a drive circuit for driving the pumping light source, a power circuit for supplying electric power to the drive circuit, and a second optical fiber for sending signal light amplified. The optical repeater has a general-purpose common frame. The common frame has an inner space defined so as to accommodate the pumping light source and the optical coupling module, and has a bobbin portion for winding at least one of the first optical fiber and the second optical fiber. The drive circuit and the power circuit sometimes differing according to the kinds of products are mounted on an individual frame detachably fixed to the common frame.