Figs. show examples of this θ dependence for a Fabry-Pérot cavity for the situation of (b) zero lightmatter energy detuning, (c) positive detuning, and (d) negative detuning, where the polariton dispersion curves are depicted in purple. For each k (that corresponds to a specific θ or k x ), the model Hamiltonian in Eq. 90 is diagonalized to find the dispersion plots. Similarly, the polariton eigenenergies are now functions of k (or equivalently, θ) as follows