Optical properties of an inhomogeneously broadened multilevel V-system in the weak and strong probe regimes

TL;DR

This paper models the optical properties of an inhomogeneously broadened multilevel V-system in rubidium, analyzing how weak and strong probe fields affect transparency, dispersion, and absorption, with implications for optical switching and group velocity control.

Contribution

It provides a comprehensive theoretical analysis of EIT in a multilevel V-system considering thermal effects, polarization dependence, and transient behavior, advancing understanding of optical control mechanisms.

Findings

Partial transparency window in weak probe regime due to interference

Increased linewidth and steep dispersion at room temperature

Transition from transparency to enhanced absorption with strong probe

Abstract

We present a theoretical model, using density matrix approach, to study the effect of weak as well as strong probe field on the optical properties of an inhomogeneously broadened multilevel V-system of the $^{87}$Rb D2 line. We consider the case of stationary as well as moving atoms and perform thermal averaging at room temperature. The presence of multiple excited states results in asymmetric absorption and dispersion profiles. In the weak probe regime, we observe the partial transparency window due to the constructive interference occurs between transition pathways at the line center. In a room temperature vapour, we obtain an increased linewidth of the transparency window and steep positive dispersion. For a strong probe regime, the transparency window with normal dispersion switches to enhanced absorption with anomalous dispersion at the line center. Here, we show how the electromagnetically induced transparency (EIT) depends on the polarizations of the applied fields. We also discuss the transient behaviour of our system which agrees well with the corresponding absorption and dispersion profiles. This study may help to understand optical switching and controllability of group velocity.