Experimental study of the statistical properties of nonlinearly amplified signals in semiconductor optical amplifiers

In this letter, we examine the effect of nonlinear amplification on the noise properties of an amplified signal. We show that the output noise statistics can be approximated as Gaussian over a wide range of practical parameters. In addition, we show that nonlinear amplification of noise carrying signals may result in an enhancement of the signal-to-noise ratio (SNR). Basic principles dictate that this can not improve the bit error rate performance of a communication link, as long as an optimal detection scheme is used. Hence, we conclude that for communication systems that exploit nonlinear amplification in semiconductor optical amplifiers, evaluation of performance on the basis of the SNR can be misleading and should be made with great care.