Use of graded-index fibers for matching injection lasers to optical fibers

The possibility is considered theoretically of using graded-index fibers in improving the coupling of injection-laser radiation into multimode and single-mode fibers. It is shown that their use enables the coefficient of coupling into multimode fibers to be increased by a factor of 1.5–3.5, relative to that when the laser is directly connected to the fiber. A coefficient of coupling into single-mode fibers of 100% can be achieved by using an appropriate graded-index-fiber light guide.