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Communications in Physics

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

Phuong Le Thi Minh, Thanh Thai Doan, Hoang Minh Dong

Published Sep 14, 2026• 0 citations
Publisher

Abstract

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.

DOI
10.15625/0868-3166/24173

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We study control of the Kerr nonlinearity and two-channel magneto-optical switching based on optical bistability behavior in a degenerate Y-type four-level atom system under a static magnetic field. This excitation configuration can provide two transparent spectral regions on the probe absorption profile. It can be transitioned between the transparency and absorption regimes by turning on or off the magnetic field in different frequency domains. We can effortlessly transform single- to double-transparency windows, and vice versa, by adjusting the strength/direction of the magnetic field. The investigations showed the enhancement of the Kerr nonlinearity around single/double-EIT windows, thereby creating single/two-channel optical bistability in these frequency regions. Particularly, flexible high-efficiency two-channel magneto-optical switching can be made based on optical bistability behavior with fixed cavity input at different frequency regions. Additionally, the coupling field intensity and the probe frequency detuning have also significantly influenced the absorption spectrum, Kerr nonlinearity, and optical bistability. The proposed model is a representative application for optical switching, storage, and nonlinear logic gates in optical communications.
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The influence of external magnetic field and relative phase between two electric field components of the probe field on absorption–dispersion and group index of a four-level atomic system with two degenerate sublevels are investigated. The results show that, the behaviors of weak probe light can be controlled by an external magnetic field. It is shown that in the presence of the external magnetic field the additional electromagnetically induced transparency (EIT) window can be obtained. Our result also reveal that the switching from slow to fast light or vice versa can be manipulated by changing the phase difference between the two circularly polarized components of a single coherent field.
Abstract We proposed a simple model for investigating subluminal and superluminal light propagation via an external magnetic field in an inhomogeneously broadened degenerate two-level atomic medium. We show that a magnetic field can be utilized as a knob to control the absorption/dispersion properties and group index of the medium. By changing the magnitude and reversing the direction of the magnetic field, the positive group index is converted to the negative group index at the center of the EIT window, corresponding with the propagation of a weak light pulse from subluminal to superluminal. Moreover, the influence of the Doppler broadening effect on the group index is also included, making the results approach to actual conditions. Therefore, the suggested model may be helpful for the application realization of optical storage in quantum computers and quantum information processing.