Electromagnetically induced grating in a thermal N-type four-level atomic system

The electromagnetically induced grating effect in thermal and cold atoms has been studied theoretically. Studies have shown that, by adjusting the parameters, the first-order diffraction efficiency of the probe beam in the cold atomic system and the thermal atomic system is 34% and 31%, respectively, which is very close to the ideal diffraction efficiency of the sinusoidal grating. However, it is more difficult to prepare the cold atomic system than to prepare the thermal atomic system in the practical application, so the study of the electromagnetically induced grating effect in the thermal atomic system may be helpful for practical applications.

Electromagnetically induced grating in a four-level tripod-type atomic system

An electromagnetically induced grating in a four-level tripod-type atomic system is studied theoretically. By virtue of a weak standing-wave signal field, the phase modulation effectively diffracts a weak probe field into the first-order direction. By changing the weak signal field, the diffraction of the weak probe field can be modulated in real time, and a first-order diffraction efficiency of more than 32% can be obtained with proper parameters. Such a system has a potential application in an all-optical switch controlled by a weak optical signal.

Effect of Phase Modulation on Electromagnetically Induced Grating in a Five-Level M-Type Atomic System

We theoretically investigate the phenomena of electromagnetically induced grating in an M-type five-level atomic system. It is found that a weak field can be effectively diffracted into high-order directions using a standing wave coupling field, and different depths of the phase modulation can disperse the diffraction light into different orders. When the phase modulation depth is approximated to the orders of π, 2π and 3π, the first-, second- and third-order diffraction intensity reach the maximum, respectively. Thus we can take advantage of the phase modulation to control the probe light dispersing into the required high orders.

Electromagnetically induced grating realization in phaseonium

We propose a method to implement electromagnetically induced grating in a phaseonium medium that has been coherently generated via atomic mechanisms.Phaseonium atoms have aΛ-type structure and three distinct energy levels;such atoms are originally generated in a coherent superposition of two lower levels.The phaseonium system is comprised of three-level atoms with aΛ-type configuration,which are initially prepared in a coherent superposition of two lower levels.To accomplish this spatial modulation based on the susceptibility of phaseonium medium,a standingwave field is used.By looking at how an optical field diffracts at different relative phases,we find that the zeroth and first order diffraction intensities increase as the relative phase changes.We also investigate the impact of the Rabi frequency of the field on diffraction intensity and notice that an increasing strength of the Rabi frequency leads to amplification in the intensity of both central zeroth order and first-order diffraction.Furthermore,it has been observed that a significant rise in diffraction intensity occurs at longer interaction lengths between external fields and the atomic medium.

Coherently induced grating in refractive index enhanced medium

We demonstrate a scheme for coherently induced grating based on a mixture of two three-level atomic species interacting with two standing-wave fields. As a result of interaction between the absorptive and amplified Raman resonances, the refractive index of the medium can be enhanced and modulated periodically. Then a sinusoidal grating, which can diffract the probe field into high-order directions, is coherently formed in the medium. The proposed scheme is theoretically investigated in a mixture of atomic isotopes of rubidium. The results show that the diffraction efficiency depends strongly on the two two-photon detunings of the two Raman transitions and the intensities of the two driving standing-wave fields. The proposed electromagnetically induced grating scheme may be applied to the all-optical switching and beam splitting in optical networking and communication.