MICROLENSES TO IMPROVE LED-TO-FIBER OPTICAL COUPLING AND ALIGNMENT TOLERANCE

The performances of four refractive concentrators in enhancing LED source-to-multimode fiber coupling are compared on the basis of improvement of coupling efficiency and relaxation of source-fiber mechanical alignment tolerances.For a core-to-source area ratio of 1.9 and a parabolic index, 0.23-N.A.fiber, experiments indicated a coupling improvement factor over butt coupling of up to 1.6, and alignment tolerance improvement factors of up to 10 (axial) or 5 (lateral) by use of an appropriate concentrator.An experimentally verified ray trace numerical simulation was used to examine the effects of fiber N.A., core area, and concentrator refractive index.© 1979 Optical Society of America.