Abstract: Variations in bending loss for relatively small radii bends along a length of optical fiber (26) are determined by using an optical time domain reflectometer (20) to measure the backscattering power as a function of distance along the fiber in one direction along the length of fiber by launching light energy into one end of the fiber. Then the backscattering power is measured as a function of distance along the fiber in the opposite direction from an opposite end by launching light energy into an opposite end of the fiber. Mathematical representations of backscattering forward and reverse signals for corresponding points along the length of the fiber are added to provide a quantity which is related to mode field diameter of the fiber. Variations in the mode field diameter are indicative of variations in the bending loss along the length of fiber. By measuring the bending loss at the end points of the length of fiber, the absolute bending loss along the length of fiber can be estimated from the above quantity.

Abstract: A method of forming optical fibers with improved mode dispersion characteristics is disclosed. The technique involves differential mode-group delay measurement to optimize dispersion by means of appropriate index of refraction configurations. The differential delay measurement technique involves selectively launching light into the multimode fiber using a single mode fiber which is spliced to the multimode fiber using an adjustable splice including an index matching fluid.

Abstract: A device (70) for switching optical signal paths of the type utilizing a plurality of light-transmitting optical fibers (40, 50) comprises a flexible elongated sleeve (20) having a longitudinally continuous interior cross section (24) with a plurality of corners (30) forming fiber-aligning grooves. The sleeve loosely receives a first fiber (40) from a first sleeve end (26) and a plurality of second fibers (50) from a second sleeve end (28). Each second fiber has its coupling end biased against an assigned corner. Also, the ends of all the second fibers are contained in one transverse plane (23). The coupling end (46) of the first fiber adjacent the transverse plane and a portion (42) of the first fiber, remote from its end, is fixedly secured to the sleeve. Coupling of the first fiber with any of the second fibers is achieved by flexing the sleeve to move the first fiber end to the corner containing the selected second fiber.