High power superluminescent diodes(SLD)havebeen fabricated from both gain guided and index guided AlGaAs/GaAs lasers. The spectral width (FWHM) of 15nm for the gain guided SLD and 8 nm for the index guided SLD are typical measured values. Output power of over 30mW/ facet is achieved for the SLD at wavelength of .83um. Over 3 mW has been obtained from the core of pigtailed single mode polarization preserving fiber. SLDsoperating at 1.3 um wave-length region has also been fabricated from index guided GaInAsP/InP lasers. Output power of 15 mW have been obtained. Coupling into single mode polarization preserving fiber with output power from fiber core over 2 mW has been achieved. Life testing of both SLDson heat sinks and single mode fiber pigtailed SLD5havebeen performed at different temperatures. Room temperature extrapolated life time of over 100,000 hours is expected.