Dark Hanle resonances from selected segments of the Gaussian laser beam cross-section

A J Krmpot,D G Slavov,M Radonjić,S N Nikolić,S M Ćuk,B M Jelenković

doi:10.1364/oe.17.022491

Abstract

We present the Hanle EIT resonances obtained from the various segments of the Gaussian laser beam cross-section, selected by moving the small aperture (placed in front of the detector) radially along the laser beam. Significant differences in the Hanle lineshapes are observed depending on whether the central or outer parts of the Gaussian laser beam are detected. The line narrowing and two counter-sign peaks occur at outer, less intense parts of the beam. The theoretical model suggests that the EIT lineshapes in the laser wings are result of the interference of the laser light and coherently prepared atoms coming from the central part of the beam. By blocking the central part of the laser beam in front of the detector, narrower, and for high laser intensities, even more contrasted Hanle resonances are obtained.

Highlights

Coherent effects in Doppler broadened alkali atom vapor have been intensively investigated over the past decade
We present the Hanle electromagnetically induced transparency (EIT) resonances obtained from the various segments of the Gaussian laser beam cross-section, selected by moving the small aperture radially along the laser beam
In this work we study EIT resonances originating from different parts of the Gaussian laser beam cross-section, after the whole laser beam passes through the Rb vapor cell

Summary

Introduction

Coherent effects in Doppler broadened alkali atom vapor have been intensively investigated over the past decade. Coherent population trapping (CPT) [1, 2], electromagnetically induced transparency (EIT) [3], and electromagnetically induced absorption (EIA) [4] have been observed and examined in either pump-probe and in Hanle configuration [5, 6] All these phenomena strongly depend on the intensity of the applied laser field. It is a reasonable assumption that different parts of the Gaussian laser beam, after passing through the alkali vapor cell, carry different information about the atomic coherence and should yield different EIT resonances. The goal of this work is in part to investigate if such mechanism plays the role in observed shape of the resonance due to the light from the wings of the Gaussian laser beam

Objectives

Results

Conclusion