Reliable, High-Speed LEDs for Short-Haul Optical Data Links

Recent advances in low-loss optical fibers have made optical fiber transmission systems one of the most promising new technologies. In a wide diversity of applications, different transmission distances and data transmission rates impose widely varying requirements in the design of fibers, light sources, detectors, and circuits used in conjunction with them. For transmission rates in excess of ~30 Mb/s over distances in excess of 5 km, high radiance sources, such as semiconductor lasers or long A L E D S coupled to small-diameter, small numerical-aperture fibers are preferred. Such restrictions would be needed to guarantee suppression of pulse dispersion and to launch sufficient power into the fiber. There are, however, other applications which require lower transmission rates over distances less than a kilometer. Such requirements can be met with inexpensive, broad-area L E D S (junction area extending over full area of chip), used in conjunction with larger core-diameter, larger numerical-aperture fibers. In this paper, a low-current density LED is 161