Continuous reversal of Hanle resonances of counter-propagating pulse and continuous-wave field

TL;DR

This paper investigates how counter-propagating continuous-wave and pulsed lasers interact in rubidium vapor, revealing conditions for controlling pulse transmission and switching between transparency and absorption via Hanle resonances.

Contribution

It demonstrates the continuous reversal of Hanle resonances in a system with counter-propagating lasers, enabling optical control of pulse propagation and resonance states.

Findings

Pulse transmission can be controlled by magnetic field and laser intensities.

Conditions identified for switching between Hanle EIT and EIA.

Strong atomic coherences enable simultaneous resonance sign reversal.

Abstract

In this work we study propagation dynamics of the two counter-propagating lasers, the continuous-wave (CW) laser and the pulse of another laser, when both lasers are tuned to the $F_{g}=2 \rightarrow F_{e}=1$ transition in $^{87}$Rb, and therefore can develop Hanle electromagnetically induced transparency (EIT) in Rb vapor. We calculate transmission of both lasers as a function of applied magnetic field, and investigate how the propagation of the pulse affects the transmission of the CW laser. And vice versa, we have found conditions when the Gaussian pulse can either pass unchanged, or be significantly absorbed in the vacuum Rb cell. This configuration is therefore suitable for the convenient control of the pulse propagation and the system is of interest for optically switching of the laser pulses. In terms of the corresponding shapes of the coherent Hanle resonances, this is equivalent to turning the coherent resonance from Hanle EIT into electromagnetically induced absorption (EIA) peak. There is the range of intensities of both CW laser and the laser pulse when strong drives of atomic coherences allow two lasers to interact with each other through atomic coherence and can simultaneously reverse signs of Hanle resonances of both.