Effects of neighboring transitions on the mechanisms of electromagnetically induced absorption and transparency in an open degenerate multilevel system

In this study, optical Bloch equations with and without neighboring hyperfine states near the degenerate two-level system (DTLS) in the challenging case of $$^{85}$$ 85 Rb D2 transition, which involves the Doppler broadening effect, are solved. The calculated spectra agree well with the experimental results obtained based on the coupling-probe scheme with orthogonal linear polarizations of the coupling and probe fields. The mechanisms of electromagnetically induced absorption (electromagnetically induced transparency) for the open $$F_g=3 \rightarrow F_e=2$$ F g = 3 → F e = 2 and 3 transitions (open $$F_g=2 \rightarrow F_e=2$$ F g = 2 → F e = 2 and 3 transitions) are determined to be the effect of the strong closed $$F_g=3 \rightarrow F_e=4$$ F g = 3 → F e = 4 transition line (strong closed $$F_g=2 \rightarrow F_e=1$$ F g = 2 → F e = 1 transition line); this finding is based on a comparison between the calculated absorption profiles of the DTLS without neighboring states and those of all levels with neighboring states, depending on the coupling and probe power ratios. Furthermore, based on the aforementioned comparison, the crucial factors that enhance or reduce the coherence effects and lead to the transformation between electromagnetically induced absorption and electromagnetically induced transparency, are (1) the power ratios between the coupling and probe beams, (2) the openness of the excited state, and (3) effects of the neighboring states due to Doppler broadening in a real atomic system.

All-Optical Switching In A Medium of A Four-Level Vee-Cascade Atomic Medium

We proposed a model for all-optical switching in a medium consisting of four-level vee-cascade atomic systems excited by coupling, probe, and signal fields. It is shown that, by changing the intensity or the frequency of the signal field, the medium can be actively switched between either electromagnetically induced transparency (EIT) or electromagnetically induced absorption (EIA), which has behavior of all-optical switching. As a result, a cw probe field is switched into square pulses by modulating the intensity or the frequency of the signal light. Furthermore, width of the square probe pulses can be controlled by tuning the switching period of the signal field. Such a tuneable all-optical switching is useful for finding related applications in optic communications and optical storage devices.

Unravelling the Mechanisms of Electromagnetically Induced Absorption and Transparency in Open Degenerate Multilevel System: Effects of Neighboring Transitions

Optical Bloch equations with and without neighboring hyperfine states near the degenerate two-level system (DTLS) in the challenging case of 85Rb D2 transition that involves the Doppler broadening effect are solved herein. The calculated spectra agree well with the experimental results obtained using the coupling-probe scheme with orthogonal linear polarizations of the coupling and probe fields. The mechanisms of electromagnetically induced absorption (electromagnetically induced transparency) for the open Fg = 3 → Fe = 2 and 3 transitions (open Fg = 2 → Fe = 2 and 3 transitions) are clearly determined to be the effect of the strong closed Fg = 3 → Fe = 4 transition line (strong closed Fg = 2 → Fe = 1 transition line) based on the comparisons of the calculated absorption profiles of a DTLS without neighboring states and those of all levels with neighboring states depending on the coupling and probe power ratios. The crucial factors established based on comparisons of the calculated absorption profiles of DTLS with and without neighboring states, which enhance or reduce coherence effects and result in transformation between electromagnetically induced absorption and electromagnetically induced transparency, are the power ratios between coupling and probe beams, openness of the excited state, and effects of the neighboring states due to the Doppler broadening in a real atomic system.