Using the Jaynes-Cummings (JC) type model Hamiltonian, we further investigated the optical spectra influenced by the light-matter coupling strength ℏg c and the cavity loss rate Γ. In this work, we focused on two particular model systems, an exciton monomer coupled to a single-mode cavity, and an exciton dimer coupled to a single-mode cavity. For an exciton monomer coupled to the cavity, the linear spectra obtained from the L-PLDM approach are in excellent agreement with the analytic answer (Eq. 57), at various light-matter coupling strengths and cavity loss rates. In particular, with an increasing cavity loss rate, we observe a decrease in Rabi splitting, which can be attributed to an effective decrease in lightmatter coupling strength due to the difference between the cavity and matter line widths.