  Stronger light intensity fluctuations are pursued by related applications
such as optical resolution, image enhancement, and beam positioning. In this
paper, an Nth-order light intensity fluctuation amplifier is proposed, which
was demonstrated by a four-wave mixing process with different statistical
distribution coupling lights. Firstly, its amplification mechanism is revealed
both theoretically and experimentally. The ratio $R$ of statistical
distributions and the degree of second-order coherence ${g^{(2)}}(0)$ of beams
are used to characterize the affected modulations and the increased light
intensity fluctuations through the four-wave mixing process. The results show
that the amplification of light intensity fluctuations is caused by not only
the fluctuating light fields of incident coupling beams, but also the
fluctuating nonlinear coefficient of interaction. At last, we highlight the
potentiality of applying such amplifier to other N-order nonlinear optical
effects.
