▎ 摘　　要

A double-band terahertz (THz) white light cavity (WLC) scheme is proposed based on the enhanced nonlinear dispersion in a four-level Y-type graphene system. Double anomalous dispersion regions occur within the transparency windows owing to the enhanced nonlinear dispersion induced by the relatively strong probe field. The cavity linewidth can be broadened by the anomalous dispersion, thus permitting to obtain a double-band THz WLC. The simulation results show that both linewidths of the nonlinear WLC are one order of magnitude larger than the empty cavity linewidth. Furthermore, THz WLC is investigated in doped graphene, where it is interesting to find that a multi-band THz WLC could be obtained with the aid of additional optical field. The proposed scheme may find potential applications in the fields of multi-band THz communications.