  We discuss in-medium propagation dynamics in a white light cavity that leads
to an enhancement of the cavity's bandwidth without reducing its maximum
intensity buildup. We analyze the spatiotemporal dynamics of our system with a
full simulation of the field propagation in a regime that leads to strong
absorption of the control fields. We find that an additional coherent field is
generated within the medium via four-wave mixing. This self-generated field
leads to a backaction of the medium onto the probe field. Counter intuitively,
this pronounced in-medium dynamics throughout the propagation leads to an
additional enhancement of the cavity bandwidth.
