It is worth noting that this differential absorption effect persists even below the lasing threshold (i.e., in the spontaneous emission regime), meaning the stimulated emission within the gain medium itself could not directly contribute to DOCP. Instead, the DOCP is predominantly induced by the thin film's asymmetric absorption. The primary role of the stimulated emission in the gain medium is to generate linearly polarized light (with equal RCP and LCP photon numbers), while DOCP is influenced by the DOP provided by the linearly polarized pump laser.