Effects of field induced quantum coherence on the absorptive lineshape of a V-type three-level system

A single electromagnetic field interacting with a V-type three-level system having two closely spaced upper levels is studied for the Doppler-free absorptive lineshape. The usual optical Bloch equations are constructed. Quantum interference between the probability amplitudes of the levels participating in a dipole allowed transition is taken into consideration. The quantum interference is manifested through the phase angle. It appears that these phases are significant only if the applied electromagnetic field is strong. The absorptive lineshape calculations are revisited in the light of such field induced coherence. The lineshape exhibits pushing between two spectral lines in addition to the usual pulling between them. It is found that the pushing of the spectral lines depends solely on the coherence induced by the strong field. The complete cancellation of field dependent shifts for the resonance peaks is possible by the suitable adjustment of the phase angles arising from the strong field induced coherence.