Coupling field dependent quantum interference effects in a $\Lambda$-system of $^{87}Rb$ atom

TL;DR

This paper explores how different coupling field configurations in a $^{87}Rb$ atom's $Lambda$-system affect quantum interference, revealing transitions between EIT and EIA with potential applications in laser locking and optical switching.

Contribution

It demonstrates the coupling field dependent transition between EIT and EIA in a $^{87}Rb$ $Lambda$-system, highlighting the effects of standing wave configurations and power variations.

Findings

Standing wave coupling transforms EIT into EIA.

High coupling power enhances EIA amplitude and slope.

EIA signals are useful for laser locking and optical switching.

Abstract

A $\Lambda$-system in $D_2$ line transition of the $^{87}Rb$ atom has been investigated for quantum interference effects for different configurations of coupling field. With a travelling wave coupling field (co-propagating with probe field), the probe beam shows the earlier known electromagnetically induced transparency (EIT) effect at the resonance. With a standing wave coupling field (which is co- and counter-propagating with probe beam), the probe EIT gets transformed into an electromagnetically induced absorption (EIA). A variation in coupling beam power has shown that, at high coupling power, EIA signals have much larger amplitude and slope than those of EIT signals with and without applied magnetic field. These EIA signals can be useful for tight laser frequency locking and optical switching.