  We investigate Jahn-Teller (JT) polaritons, which emerge from the interaction
of the two normal-incidence electromagnetic modes with perpendicular
polarizations in a Fabry-Perot cavity resonator with JT active systems. These
JT polaritons are characterized by a mixed $(+/-)$--circular electromagnetic
polarization that originates from the molecular JT vibronic coupling of the
material subsystem. Consequently, the exchange of photonic and vibronic angular
momenta can be very efficient; exciting the cavity-JT system with short,
polarized light pulses results in a dynamical and oscillatory response of the
polarization in the cavity medium. Due to the photonic-vibronic coupling, we
show how the cavity polarization direction becomes frequency dependent and does
not necessarily coincide with the polarization direction of the external fields
used to drive the system.
