Abstract: The invention provides an optical-coupler reinforcing member for fixing and reinforcing a fiber-coupler body and a method of performing the reinforcing. The reinforcing member includes heat-shrinkage tubes which are shrunk by heating, and a hollow protection pipe provided in the heat-shrinkage tubes. Cylindrical heat-fusible adhesive members are provided on opposite ends of the protection pipe, and heating is made such that a fusing portion of an optical-fiber coupler body is inserted through the reinforcing member so that the heat-fusible adhesive members and the heat-shrinkage tubes are shrunk by heating to thereby fix and reinforce the optical coupler body.

Abstract: A reinforcing apparatus for an optical-fiber coupler is formed by placing fused optical fibers into a grooved U-shaped base structure. A cover which has a different longitudinal length than the base structure is centered on top of the U-shaped base structure. There exists an exposed groove section of the U-shaped base structure which lies on either side of the cover. An adhesive is inserted into these exposed groove sections so as to fix the reinforcing casing and the optical-fiber coupler to each other.

Abstract: A method of reinforcing a multiple optical fiber coupling unit is provided including the steps of removing a portion of longitudinal coatings of optical fibers of the multiple optical fiber coupling unit to expose glass portions of said optical fibers; fusing a portion of the exposed glass portions so as to optically couple the optical fibers; extending the fused portion to a predetermined state; fixing non-extended portions of the exposed glass portions on a first reinforcing substrate with a first adhesive; and fixing the first reinforcing substrate on a second reinforcing substrate with a second adhesive. The multiple optical fiber unit coupler made by this method has a transmission characteristic that does not substantially change even with a temperature change and under high humidity.

Abstract: A waterproof optical fiber cable comprising at least one coated optical fiber and a waterproof compound surround said at least one coated optical fiber, wherein a swelling degree of a coating material of the optical fiber induced by said waterproof compound is not larger than 10%, which optical fiber cable has stable performances.