In this talk we predict how a material excitation with a dispersive gain profile couples with light in a microcavity. We show that even a single transition yields an interacting set of coupled intersubband polariton [1] and antipolariton [2] branches which can potentially lead to a new level of all-optical control and switching in a microcavity. In contrast to the conventional antipolariton case with an imaginary Rabi frequency, the dilute nitride quantum wells chosen [3] show ample flexibility to engineer the dispersive gain shape without global inversion and have potential for real Rabi frequencies with measurable oscillations, suggesting this as the medium of choice to investigate the coupling of photonic modes with an excitation delivering dispersive gain.

Furthermore we show how a valence band excitation couples with TE-polarized THz radiation in a microcavity. This configuration would allow easier measurements of polaritons [1] and antipolaritons [2] without the need to grow the resonator in a slanted prism, as in usual TM mode, conduction band realizations. A Nonequilibrium Many Body approach delivering an optical response beyond the Hartree-Fock approximation allows the study of multiple transitions and an interesting picture of interacting polaritons and antipolaritons develops due to the coexistence of gain and cross absorption to higher subbands.

[1] D. Dini, R. Köhler, A. Tredicucci, G. Biasiol, and L. Sorba, Phys. Rev. Lett. 90 116401 (2003).
[2] M.F. Pereira Jr., Phys. Rev. B75, 195301 (2007).
[3] M.F. Pereira Jr and S. Tomi?, Appl. Phys. Lett. 98, 061101 (2011).