High radiance InGaAsP/InP lensed LED́s for optical communication systems at 1.2-1.3 µm

The fabrication of high radiance InGaAsP/InP double-heterostructure (DH) surface-emitting LED's at 1.27 μm wavelength has been described. The elimination of the junction misplacement as well as the optimization of the active layer thickness has been found to be important in realizing high quantum efficiency. An ideal DH, free from the junction misplacement, has been fabricated by using Cd as the dopant in the InP carrier confining layer. The active layer thickness for maximum output power has been determined to be
1-1.5 \mu
m. Furthermore, a new fabrication technique has been developed and the LED structure, which has a lens monolithically formed on the InP substrate, has been fabricated for the first time at this wavelength. This lensed LED improves the coupling efficiency greatly, 2.7 times that of the flat LED's. A maximum coupled power of approximately 0.20 and 0.31 mW has been attained at 100 mA for 85 μm core, 0.16 NA and 100 μm core, 0.25 NA step index fibers, respectively.