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Abstract: The dynamic evolution of a Λ system coupled by two strong coherent fields is investigated by taking spontaneously generated coherence (SGC) into account. By numericaly simulation, it is shown that the relative phase of the two coherent fields affects significantly the time scale to the coherent population trapping state. In addition, an analytical expression to the evolution rate which is consistent with the numerical results is given. [Copyright &y& Elsevier]

The effect of spontaneously generated coherence (SGC) on the pump–probe response of a nearly degenerate Λ system is investigated by taking into account the dephasing of the low-frequency coherence. It is found, in the case of small dephasing, that instead of electromagnetically induced transparency (EIT) at resonance, electromagnetically induced absorption (EIA) can occur due to the effect of SGC. We also study the effect of relative phase between the two applied fields and find that EIA and EIT can transform mutually by adjusting the relative phase. [Copyright &y& Elsevier]

Spontaneous emission can create coherence in a ladder-type three-level atom with equispaced levels, subject to the condition that the atomic dipole moments are nonorthogonal. We study the effects of this kind of coherence on the steady-state population inversion in the atomic system. We show that the population inversion can be greatly enhanced on one of the optical transitions due to the spontaneous emission-induced coherence. Furthermore, we find, within suitable parameters regions, that such coherence can also lead to unexpected population inversion on both of the optical transitions. [Copyright &y& Elsevier]