THE COUPLING OF LIGHT FROM LIGHT-EMITTING DIODES INTO OPTICAL FIBERS: THE ANALYSIS OF CLOSE-COUPLING

摘要

The efficiency of coupling light from a lightemitting diode (LED) into a fiber or fiber-optic bundle has been determined using meridional ray and skew ray tracing techniques. Light loss due to Fresnel reflection was included in the efficiency calculations. The results indicate that the most important factor affecting the efficiency is the angular distribution of the light from the LED. It is shown that efficient coupling into a lownumerical-aperture fiber requires the use of a lens or reflector to narrow the angular distribution of the light from the LED. The results of the skew ray analysis indicate that the coupling efficiency is a function of the LED diameter, and this relation provides a technique for determining the contribution of skew rays to the power in the field.