Negative Refractive Index in an Inhomogeneously Broadened Four-Level Inverted-Y Atomic Medium

Bang Nguyen,Nguyen Cong,Vu Sau,Nguyen Phu,Doai Le Van

doi:10.1109/jphot.2021.3119985

Bang Nguyen, Nguyen Cong + Show 3 more

Open Access

https://doi.org/10.1109/jphot.2021.3119985

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Journal: IEEE Photonics Journal	Publication Date: Dec 1, 2021
Citations: 2	License type: CC BY 4.0

Affiliation: Vinh University

Abstract

In this paper, we present the study on negative refractive index in an inhomogeneously broadened four-level inverted-Y atomic medium based on electromagnetically induced transparency (EIT). The expressions of the relative permittivity and the relative permeability are derived under Doppler broadening. For this four-level system, we have found two frequency bands of negative refractive index in an optical region corresponding to two EIT windows. The influences of coupling and signal laser fields as well as temperature on frequency bands of negative refractive index are investigated. Our research can be convenient for experimental implementation with real atomic media under different temperatures.

Highlights

T HE electromagnetically induced transparency (EIT) is a quantum interference phenomenon which renders a medium transparent for a weak probe field induced by a strong coupling field [1], [2]
Negative refractive index in an inhomogeneously broadened four-level inverted-Y atomic gas medium is achieved in two optical frequency bands
The frequency bands of negative refractive index are controlled by the intensity and the frequency of coupling and signal laser fields

Summary

INTRODUCTION

T HE EIT is a quantum interference phenomenon which renders a medium transparent for a weak probe field induced by a strong coupling field [1], [2]. In addition to vanishing absorption, EIT material possesses a controllable high refractive index, so it has many novel interesting applications such as slow light, lasing without inversion, giant nonlinearity, controllable optical bistability, and so on [2] Thanks to such unusual properties of the EIT material, it is of great interest to realize a negative refractive index in isotropic atomic gas media. We present the realization of negative refractive index in a Doppler broadened four-level inverted Y-type atomic medium. This four-level inverted-Y scheme is consisted of two sub-systems Λ + Ξ, so it can exhibit two transparency windows for the probe laser field [35].

THEORETICAL MODEL

RESULTS AND DISCUSSION

CONCLUSION