The coupling of light-emitting diodes to optical fibers using sphere lenses

Abstract

The use of a truncated sphere of high-refractive-index material is proposed as a lens designed to improve the coupling efficiency between a light-emitting-diode source and an optical fiber. A method of calculating the coupling efficiency for such lens systems is described. Numerical results for the variation of efficiency with lens parameters are presented and discussed for coupling to a fiber bundle with a numerical aperture of 0.14. Improvements of two orders of magnitude in the coupling efficiency over that attainable with the close coupling geometry are predicted.