  The coupled cubic nonlinear Schr\"odinger (CNLS) equations are used to study
modulational instabilities of a pair of nonlinearly interacting two-dimensional
waves in deep water. It has been shown that the full dynamics of these
interacting waves gives rise to localized large-amplitude wavepackets (wave
focusing). In this short letter we attempt to verify this result numerically
using a Fourier spectral method for the CNLS equations.
