  We have demonstrated, both theoretically and experimentally, that it is
possible to control (i.e., to enhance or cancel) the contrast of the
interference pattern appearing in the intensity images obtained with a laser
optical feedback imaging (LOFI) setup using a bimode laser. The laser is
composed of two coupled orthogonally polarized states that interact (i.e.,
interfere) through the cross saturation laser dynamics. We created the contrast
control by choosing the frequency shift (i.e., the beating frequency) between
the feedback electric fields and the intracavity electric fields. We have shown
that the interference contrast of the output power modulation of the laser
total intensity is independent from the frequency shift and is always maximal.
On the other hand, the interference contrast of each polarization state is
frequency dependent. We obtained the maximal contrast when the frequency shift
was equal to one of the resonance frequencies of the bimode dynamics, and was
very low (and almost cancels) for an intermediate frequency located at the
intersection of the two resonance curves.
