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The performance and reliability of InGaAsP/InP double heterostructure (DH) light emitting diodes (LED's) have been investigated over a wide range of emission wavelengths m. High radiance performance has been achieved by growing optimized DH structures and adopting a method of coupling a monolithic-lensed LED to a spherical-ended fiber. Interface instability previously encountered in the liquid phase epitaxy (LPE) to grow a DH for 1.5 μm wavelength has been eliminated by a new growth method using a reduced temperature. LED's exhibiting typical output powers of 50, 44, and 21 μW at 100 mA, measured at the end of a 50 μm core 0.20 NA graded-index fiber with a length of 1 m, have been realized, respectively, at wavelengths of 1.15, 1.27, and 1.5 μm. The spectral width, coupled power and its temperature dependence, and the cutoff frequency have been analyzed in terms of the emission wavelength. Operating lives of LED's at three different wavelengths have been estimated from the result of accelerated aging carried out at the ambient temperature of 200°C and at a constant current of 100 mA. It has been found that the degradation rate exhibits no dependence on the wavelength confirming the same value of half-lives in excess of 109h for the 60°C operation.