  Effects of rotational mode coupling on photometric parameters of stellar
oscillations are studied. At moderate rotation rates, a strong coupling between
modes of spherical harmonic degree, $\ell$, differing by 2 and of the same
azimuthal order, $m$, takes place if the frequencies are close. This is a
common situation amongst main sequence pulsators. Numerical results for a
sequence of $\beta$ Cephei star models are reported for the two- and three-mode
couplings.
  One consequence of mode coupling is that modes of higher degree should be
considered in photometric mode identification. Modes with nominal degree
$\ell>2$ acquire substantial $\ell\le2$ components and therefore are more
likely to reach detectable amplitudes. Coupled mode positions in the amplitude
ratio - phase difference diagrams, based on multicolour photometry, become both
aspect- and $m$-dependent. Examples of the mode path in the diagram with
varying aspect are given. The diagrams remain a useful tool for mode
identification in rotating stars but the tool must be used with care.
