Dynamic of two-channel pulse propagation in a tripod-type degenerate atomic medium

We numerically investigate two-channel pulse propagation dynamics in a degenerate tripod-type four-level atomic medium under the combined influence of an external magnetic field and a relative phase. The results show that an external magnetic field is used as a “knob” to switch between transparent and absorptive regimes of the probe pulse by the on/off state of the magnetic field within suitable frequency and phase domains. By tuning the magnitude of the magnetic field, the transparency spectrum can be reversibly transformed between single- and double-window structures, enabling stable pulse propagation in a single- or dual-channel. In addition, the relative phase strongly modifies the probe absorption profile and provides an efficient means to control pulse propagation dynamics. These findings suggest promising applications in pulse propagation, multi-channel switching, and optical storage for communication systems.