Abstract: Optical coupling apparatus for coupling a portion of the optical energy propagating through each individual optical fiber of an optical transmission system into an associated optical fiber is disclosed. The coupling apparatus utilizes a single semi-reflective beam splitting interface that is angularly disposed between associated optical fibers that form input and output sections of each individual transmission path of the optical transmission system. An optical fiber is arranged relative to the semi-reflective interface and the associated input and output fibers of each optical transmission path so as to form a plurality of optical Tee type couplers. As optical signal energy propagates from each individual input fiber, a portion of the optical energy passes through the beam splitting interface into the associated output fiber and the remaining portion is reflected from the interface into the third optical fiber.