Abstract

We present new results of measurements of ultrafast gain saturation in GaAlAs laser amplifiers using a pump and tunable probe technique. To our knowledge these are the first subpicosecond, time-resolved, non-degenerate four-wave mixing experiments performed in laser diodes. Our tunable probe allows the observation, throughout the gain bandwidth of the amplifier, of gain changes caused by the passage of a fixed wavelength, 350 fs pump pulse. We observe a similar gain saturation at all wavelengths, indicating a mechanism other than spectral hole burning is responsible for the observed subpicosecond cross-modulation.

© 1988 Optical Society of America