▎ 摘　　要

We have numerically investigated the required minimum cavity dispersion (RMCD) for obtaining stable pulses in net normal dispersion, graphene mode-locked, Yb-doped fiber lasers (YDFLs). By solving the modified nonlinear Schrodinger equation, we have found that the value of the RMCD was mainly affected by the nonsaturable absorption losses in the graphene saturable absorber (SA), and when monolayer graphene was used as the SA, this value was less than that obtained using multilayer graphene as the SA. We have also found that monolayer graphene YDFLs were more suitable for generating high-power, narrow-width pulses than were multilayer graphene YDFLs.