  A major objective in photonics is to tailor the emission properties of
microcavities which is usually achieved with specific cavity shapes. Yet, the
dynamical change of the emission properties during operation would often be
advantageous. The implementation of such a method is still a challenging issue.
We present an effective procedure for the dynamical control of the emission
lobes which relies on the selection of a specific coherent superposition of
degenerate modes belonging to different symmetry classes. It is generally
applicable to systems exhibiting pairs of degenerate modes. We explored it
experimentally and analytically with organic square microlasers, which emit
narrow lobes parallel to their sidewalls. By means of the pump polarization,
emission lobes are switched on and off selectively with an extinction ratio
better 1/50.
