Realization of a negative refractive index in a three-level Λ system via spontaneously generated coherence

Dutta, Sulagna; Dastidar, Krishna Rai

doi:10.1088/0953-4075/43/21/215503

Cited by 15 publications

(4 citation statements)

References 44 publications

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“…The existence of SGC effect depends on the non-orthogonality of the two dipole transition moments, which can be obtained from the mixing of the levels arising from internal fields such as, for example, the superposition of singlet and triplet states due to spin-orbit coupling in sodium dimers [36] or by external fields, as shown previously [37][38][39]. In our previous work, we have also shown how SGC in molecules can be invoked by an external field [34,40].…”

Section: Resultsmentioning

confidence: 65%

The incoherent pump rate: an optical tool for controlling the probe response and dispersion in a three-level Λ system in the presence of spontaneously generated coherence

Dutta

2010

Phys. Scr.

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The probe response and dispersion of a three-level closed system considering spontaneously generated coherence (SGC) have been investigated with and without an incoherent pumping. One can get electromagnetically induced transparency (EIT) whatever be the value of the SGC parameter and phase difference when an incoherent pump is absent. But by turning the incoherent pump rate on, one can control the light propagation from subluminal to superluminal and also the nonlinear response from EIT to electromagnetically induced absorption (EIA) by controlling the SGC parameter and phase difference. Using the incoherent pump rate as an optical tool, the desired configuration around the resonance can be realized. Exact analytical expressions for the coherences in the steady-state limit have been derived in the absence of an incoherent pump rate (keeping all orders of the system parameters) to generalize the analysis, and any restriction on the system parameters has been avoided to make it applicable to various atomic and molecular systems.

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Section: Resultsmentioning

confidence: 65%

The incoherent pump rate: an optical tool for controlling the probe response and dispersion in a three-level Λ system in the presence of spontaneously generated coherence

Dutta

2010

Phys. Scr.

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“…Since then, several other studies on negative refractive index have been carried out in four- [21][22][23][24][25][26] and five- [27] level atomic systems that can be easily generated negative refractive index in different frequency bands. Recently, some authors have used the SGC effect to achieve negative refractive index with significantly reduced absorption and to control the frequency band of negative refractive index according to laser parameters and quantum interference parameter [28][29][30]. Under SGC condition, the refractive index can be switched from positive to negative or vice versa by varying the relative phase of laser fields and the strength of SGC.…”

Section: Introductionmentioning

confidence: 99%

Negative refractive index in a Doppler broadened three-level Λ-type atomic medium

Ai¹,

Bang²,

Doai³

2022

Phys. Scr.

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We have achieved a negative refractive index with significantly reduced absorption in a three-level Λ-type atomic gas medium under Doppler broadening. It shows that the conditions for obtaining negative refractive index in the presence of Doppler broadening are very different from those of Doppler broadening absent. In particular, in order to obtain negative refractive index in the case of Doppler broadening the coupling laser intensity must be approximately ten times greater than that when the Doppler broadening is ignored. Meanwhile, the frequency band of negative refractive index with Doppler broadening is significantly expanded (about a hundred times) compared to that without Doppler broadening, however, the amplitude of negative refractive index decreases with increasing temperature (or Doppler width). Even in some cases as temperature (Doppler width) increases, the left-handedness of the material can disappear. In addition, we also show that the amplitude and the frequency band of negative refractive index can be changed by adjusting the intensity and the frequency of coupling laser. Our theoretical investigation can be useful for selection of laser parameters under different temperature conditions to achieve negative refractive index in experimental implementation.

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“…Later Shen et al [35] suggested a scheme based on a quantum mechanical approach to realize negative permeability in a Ã system and proposed that if one mixes the negative permeability vapour with Agarwal et al's negative permittivity vapour [34], the produced mixed atomic vapour may exhibit left-handedness for the probe light. Very recently we have proposed a new scheme to realize simultaneous negative permittivity and permeability in a three-level closed system neglecting the local field effect [36,37].…”

Section: Introductionmentioning

confidence: 99%

Study of group velocity in the negative refractive index region in three level closedΛsystem via spontaneously generated coherence

Dutta

Dastidar

2012

Molecular Physics

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A new approach is suggested to realize simultaneous negative permittivity and permeability in a three level closed system with incoherent pumping via spontaneously generated coherence (SGC). In this system the negativity of the real part of magnetic permeability can be achieved in the presence of SGC whereas in the absence of SGC it is positive. Thus the SGC makes the system a negative index medium (NIM) in a band of frequency range. The position and the band of the frequency region of negative refraction can be manipulated by controlling the incoherent pump rate. We achieve FOM ¼ 7.91165. We have studied the group index in the negative refractive index region and have shown that the group velocity switches from superluminal to subluminal mode in this region of negative refraction. We have shown that the negative refractive index can be realized in a heteronuclear molecule.Keywords: negative refractive index; spontaneously generated coherence IntroductionThe left-handed materials (LHMs), first introduced by Veselago [1], have recently attracted much attention because of their surprising and counterintuitive electromagnetic properties. Such materials possessing negative real parts of both dielectric permittivity ( r ) and magnetic permeability ( r ) over a certain frequency band characterize a negative value of the refraction denoted by real part of an index n ¼ À ( r r ) 1/2 [1][2][3][4][5][6][7][8][9][10][11]. These LHMs exhibit a number of peculiar electromagnetic and optical effects including the reversals of both Doppler shift and Cherenkov radiation [1], anomalous refraction [1], amplification of evanescent waves [3], subwavelength focusing [3,5], a negative Goos-Ha¨nchen shift [6], a reversed circular Bragg phenomenon [7], photon helicity inversion [8], some unusual photon tunnelling effects [9], reversed H field circulation patterns and inverted E field lines in propagating structures [10], and switched field intensity locations in anisotropic transmission structures [11].Although naturally occurring materials with simultaneous negative permittivity and permeability are not available, LHMs can be artificially realized. There are several ways to realize LHM, including artificial composite metamaterials [12][13][14][15], photonic crystal structures [16][17][18], transmission line simulation [19] and chiral material [20][21][22][23]. These methods based on

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Realization of a negative refractive index in a three-level Λ system via spontaneously generated coherence

Cited by 15 publications

References 44 publications

The incoherent pump rate: an optical tool for controlling the probe response and dispersion in a three-level Λ system in the presence of spontaneously generated coherence

The incoherent pump rate: an optical tool for controlling the probe response and dispersion in a three-level Λ system in the presence of spontaneously generated coherence

Negative refractive index in a Doppler broadened three-level Λ-type atomic medium

Study of group velocity in the negative refractive index region in three level closedΛsystem via spontaneously generated coherence

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