Control of probe response and dispersion in a three level closed Λ system: Interplay between spontaneously generated coherence and dynamically induced coherence

J. Phys. B: At. Mol. Opt. Phys.

2010

Self Cite

A new scheme to realize simultaneous negative permittivity and permeability in a three-level closed Λ system with incoherent pumping via spontaneously generated coherence has been presented. We have shown that the negative refractive index can be realized in a heteronuclear molecule such as LiH. The negative refractive index can be achieved 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 a figure of merit (FOM) = |Re(n)/Im(n)| = 1.797 for the LiH molecule.

Section: Introductionmentioning

confidence: 91%

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

Dutta

J. Phys. B: At. Mol. Opt. Phys.

2010

Self Cite

“…Thus we obtain equations in redefined density matrix elements ij which are found to be identical to Equations (1)-(6), with the SGC parameter 0 replaced by ¼ 0 exp(i), G p replaced by G and O c replaced by O, where G and O are treated as real parameters. Previously we have shown that the exact expressions for coherences and populations can be derived analytically without any approximation [39] and here we will use these expressions to obtain the susceptibilities and group velocity.…”

Section: Theoretical Modelmentioning

confidence: 99%

“…In our previous work [38,39], we analytically solved the density matrix Equations (1)-(6) in the steady state limit without any approximation, i.e. keeping all the orders of both the probe field and coherent field Rabi frequencies, spontaneous decay rates and incoherent pumping and obtain the exact analytical steady state value of the polarizations 13 and 23 .…”

Section: Theoretical Modelmentioning

confidence: 99%

“…However, when G ( O, EIT can not be achieved in our scheme. Using exact analytical expressions for Re( 13 ) and Im( 13 ) from Equations (7) and (27) of [39], the analytical value of the real and imaginary part of r can be calculated.…”

Section: Theoretical Modelmentioning

confidence: 99%

“…This is true when the dipole transition moments on the probe and coherent field transitions are orthogonal. However, the situation is completely different when the dipole transition moments from the upper level to two closely lying lower levels are nonorthogonal [38][39][40][41][42][43]. In this case another coherence, i.e.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

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

Dutta

2012

Molecular Physics

Self Cite

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

Electromagnetically induced transparency with quantum interferometry

Bhattacharjee¹,

The Journal of Chemical Physics

2012

We have shown that electromagnetically induced transparency can be achieved by control-probe interferometry using two delayed phase-locked ultrashort pulses. Two vibrational wavepackets on the excited state, excited by two delayed phase-locked ultrashort pulses, interfere constructively or destructively leading to enhancement or suppression of absorption to a selective set of vibrational levels. Depending on the phase difference and the delay between the pulses with same carrier frequency, one can design different transparency windows between absorption peaks at consecutive even(odd) vibrational levels by eliminating absorption at odd(even) vibrational levels. We have shown that by switching the phase difference of two delayed femtosecond pulses, one can switch to complete elimination of absorption from enhanced absorption to a particular set of vibrational levels in the excited state. Thus, switching of transparency through window between odd vibrational levels to that between even vibrational levels is possible. By properly choosing the temporal width and the carrier frequency of the pulses, lossless transmission of complete or bands of frequencies of the pulses can be achieved through these transparency windows. Hence, designing of single- or multi-mode transparency windows in NaH molecule is feasible by control-probe quantum interferometry.