We report diode-pumped Er3+:Y2O3 ceramic laser with ~14 W of true CW output at ~2.7 μm. This presents nearly ten-fold power increase with respect to previous best result with this laser material. We also believe this to be the highest power ever reported from Er3+ -doped bulk crystalline laser operating in a ~3-μm wavelength range. Power-scaled performance of 974-nm pumped Er3+:Y2O3 laser was achieved with the slope efficiency of ~26%.

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The behavior of delaminated graphite/epoxy composites under variable amplitude compressive loading (spectrum loading) is studied. The delamination growth is monitored in real time during fatigue tests. Different variable amplitude compressive load spectra are applied. Calculations of the energy release rate, G, as a function of the delamination length, delamination position, and applied strain during the spectrum loading are performed. Numerical simulations are based on a mixed mode fatigue growth model that is not subjected to the thin film model restrictions. The higher energy release values during the overloads were associated to the formation of intralayer and interlayer cracks on the composite specimens. [S0094-4289(00)03004-8]

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