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We have measured the room-temperature intensity dependence of the optical transmission of an In(0.53)Ga(0.47)As/In(0.52)Al(0.48)As multiple-quantum-well structure from 1.5 to 1.7 microm. The absorption is calculated from the transmission by taking into account the wavelength dependence of the reflection coefficients. An intensityof 15 kW cm(-2) is required to reduce the absorption by one half for excitation at the edge of the 1H-lC transition absorption band. For intensities exceeding 10(7) W cm(-2), complete saturation of the absorption is observed. A theoretical model is described that fits the intensity dependence of the absorption right upto saturation at two wavelengths and predicts a carrier lifetime of 0.75 nsec, which has been confirmed by independent measurements.

The sub-band energies of In,Ga, .As quantum wells strained between GaAs barriers and substrate are calculated using a model which takes into account strain, non-parabolicity and quantum well effects. A comparison is made with low-temperature photoluminescence and photoluminescence excitation spectra of In,Ga, .As quantum wells for which x=0.28. The transitions 1H-IC. 1L-IC and 2H-2C have been identified for the 7.5 nm well.

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