A New type GaAlAs monolithic lens coupled LED has been proposed and developed to achieve the highly efficient performance for fiber-optical communications. A GaAlAs lens monolithically formed on the LED surface and the spherical-ended fiber are efficiently coupled under the optimized design. Using the lensed LED having the magnification β of 2, the efficiency was improved 4 times better than that of flat LED. The lens radius of 80μm and thickness of 60 μm are chosen. The improvement factor β2 in efficiency was confirmed for β of from 1.6 to 2.2. For LED with the emitting diameter of 20 μm, at the forward current of 100mA, powers of 0.7 and 1.2 mW were coupled into 0.16 N A, 85 μm core, and 0.28 N A 100 μm core step index fibers, respectively.
