Crosstalk between intensity-modulated wavelength-division multiplexed signals in a semiconductor laser amplifier

The performance of a 1.5- mu m Fabry-Perot type laser amplifier having two input signals at different wavelengths is experimentally studied. Crosstalk between the two signals at the output of the amplifier is measured. The crosstalk is strongly dependent on the input powers and on the signal gain, and is found to be very sensitive to the relative wavelengths of the input signals. The crosstalk can be either positive or negative, depending on the wavelength offsets. A theoretical model taking gain saturation and wavelength shift of the amplifier spectrum into account is shown to explain the experimental results well. Using this model, some general aspects on crosstalk in semiconductor laser amplifiers are discussed.<>