Abstract: An optical fiber hermetic fixing structure of a feedthrough for an optical submarine repeater in which at least one optical fiber is introduced into a fluid-tight pressure-resistant housing of an optical marine repeater. Optical fibers are introduced and disposed in a through opening defined between a metal fiber-supporting guide and a metal sealing sleeve circumferentially of the fiber-supporting guide. The guide has a somewhat reduced diameter adjacent an end of the through opening so that the through opening has a greater transverse dimension along this part adjacent a seawater end of the feedthrough. This part of the through opening is filled with a low temperature melting metal about and between the optical fibers extending therethrough. The low melting temperature metal extends out of the through opening with a generally conical cross section configuration. A protective cover cap is disposed coaxial with the sleeve and fiber-supporting guide and through which the optical fibers extend longitudinally.

Abstract: A spliced portion housing structure for an optical fiber in an optical submerged repeater, characterized in that, in order to splice together in a joint ring an optical fiber and a power-supplying feeder from the optical submerged repeater to an optical fiber and a power-supplying feeder of a tail cable from a cable coupling of an optical submarine cable, respectively, a joint chamber is provided on an end plate of a housing of the optical submerged repeater in such a manner that the end plate forms a part of the joint chamber; the optical fiber and the power-supplying feeder from the submerged repeater are introduced into the joint chamber through a first feedthrough provided in the end plate for hermetically introducing the optical fiber and the power-supplying feeder; the tail cable from the cable coupling is hermetically introduced into the joint chamber through a second feedthrough provided in the wall of the joint chamber so that the tail cable is insulated from the joint chamber, the optical fibers and

Abstract: An optical fiber submarine cable, which is provided with at least one coated optical fiber, a power supplying, pressure resisting layer of a pipe-like configuration, a tension resisting wire layer formed of a conductive material of relatively low conductivity and disposed in close contact with the power supplying, pressure resisting layer of the pipe-like configuration, and an insulator layer disposed around the tension resisting wire layer. The power supplying, pressure resisting layer is formed as at least one inner layer and an outer layer.

Abstract: An optical fiber unit for optical submarine cables, in which glass portions formed by a plurality of optical fibers each having at least one coating layer and twisted together at a required pitch are embedded in a resin layer. Adjacent two layers of the coating layer and the resin layer are formed of the same material or materials which satisfy the following condition; ##EQU1## where E.sub.1 is the Young's modulus of the inner one of the two layers, E.sub.2 is the Young's modulus of the outer one of the two layers, .nu..sub.1 is the Poisson's ratio of the inner one of the two layers and .nu..sub.2 is the Poisson's ratio of the outer one of the two layers, the thus coated portion being formed over the entire length of the optical fibers or at desired intervals.

Abstract: A feedthrough terminal for optical fiber cables (12), particularly for use in an underwater repeater, comprises a rod (22) received snugly in a tube (21) and having grooves (24), which are filled by a mass of solder (26) with the optical fiber cables placed in the respective grooves. The grooves may be formed along the tube inside surface or on opposing portion of the tube and the rod. The tube and/or the rod may be possessed of a recessed surface to provide a gap for the solder mass.

Abstract: An optical fiber introducing equipment for an optical submerged repeater, in which for introducing an optical fiber for optical communication into an optical submerged repeater housing through an introducing hole, the coating of the portion of the optical fiber to be disposed in the introducing part is entirely removed for a suitable length; the coated optical fiber having the exposed fiber portion is inserted into a small-diametered metal cylinder having an insertion hole which has an inner diameter more than several times as large as the outer diameter of the coated optical fiber; an adhesive whose volume remains substantially unchanged even if hardened is filled between the optical fiber and the insertion hole to unite the optical fiber and the metal cylinder; seawater preventing means is provided on the outside of the adhesive for preventing the adhesive from making direct contact with seawater; and the metal cylinder is disposed in the introducing hole provided at a part of the repeater housing.

Abstract: An optical fiber feedthrough for an optical submerged repeater for use in an optical fiber submarine cable, in which a metal film is coated on the outer peripheral surface of an optical fiber to be introduced into the repeater, and in which a thermoplastic material, such as polyethylene or the like, is filled between the inner wall of a hole made in an end face plate of a pressure resisting container of the repeater and the metal film.

Abstract: A feedthrough for optical submerged repeater, in which a clad part of an optical fiber to be introduced into the feedthrough is given a metal coating; the coated part is inserted into a small-diametered metal pipe to be hermetically fixed between the optical fiber and the small-diametered metal pipe as by soft solder; and the small-diametered metal pipe is inserted into a disc sleeve to hermetically fix them as by brazing. Between the disc sleeve and a metal body housing the disc sleeve, polyethylene is molded for electrical insulation therebetween and for holding air-tightness against seawater, and at the side of the disc sleeve facing toward seawater or at both sides of the disc sleeve, an insulator of the optical fiber cable and polyethylene of the abovesaid molding are molded to be contiguous to each other. The abovementioned metal body is fixedly attached to the end face plate of the pressure resisting casing in a manner to provide an air-tight structure.

Abstract: An optical fiber submarine cable, in which a high viscosity material of good wettability containing air gaps is filled in a space between an optical fiber cord having housed therein at least one coated optical fiber and a pressure resisting material layer having housed therein the optical fiber cord for protecting it from seawater pressure. The air gaps and the high viscosity material are arranged alternately with each other in the space at suitable intervals in the lengthwise direction of the cable. Alternatively, the air gaps are contained in the form of bubbles in the high viscosity material.