The photonic densities of states (PDS) of the eigen polarizations (EPs) in a cholesteric liquid crystal (CLC) filled with the Fabry-Perot (FP) resonator are calculated. We obtained the dependences for the PDS on the FP resonator plates refractive indices. We showed, that the decrement and increment of the FP resonator plates refractive indices (started with the value, n = n<sub>m</sub> , where n<sub>m</sub> is the mean value of the CLC refractive index) lead to a sharp increase of the maximum PDS and, consequently, lead to a sharp decrement of the laser excitation threshold. The absorption and emission peculiarities of this system are investigated too. It is shown that the subject system can work as a low threshold laser.
We investigated the zone structure peculiarities and the photonic density of states (PDS) of the eigen polarizations (EPs) in the system composed of a stack of layers of a cholesteric liquid crystal (CLC) and an isotropic medium. The problem was solved by Ambartsumian’s layer addition modified method. The influence of the CLC sublayer thicknesses and the thicknesses of the isotropic media layers on the reflection an PDS spectra of the system is investigated.