To explain the trends of DOCP in the Fig. and the influence of pump energy on the polarization state, we explore the fundamental mechanism behind the generation of the DOCP during the pulse evolution process under stimulated emission in our chiral laser system. Under vertically polarized pump light, the achiral dye laser medium primarily emits linearly polarized light (as experimentally confirmed in the normal cavity configuration), which can be treated as having equal photon populations for RCP and LCP light. The DOCP in the simulation is given by: