Electromagnetically induced transparency of weak and powerful short laser radiation pulse

The conclusions of a theoretical study of the dependence of the characteristics of the phenomenon of electromagnetically induced transparency on the pulse intensity of the input probe radiation under elliptical polarization of laser fields have been reported. The analysis has been carried out for the $\Lambda$-scheme of inhomogeneously broadened quantum transitions between the levels $^{3}P_{0}$, $^{3}P_{1}^{0}$, and $^{3}P_{2}$ of the $^{208}$Pb isotope. The cases of resonance, i.e., the coincidence of the frequencies of the probe and control fields with the central frequencies of the corresponding quantum transitions, and quasi-resonance, when such a coincidence occurs only up to the line width of the corresponding quantum transition, have been considered. It has been shown that in these cases there is a tendency for the input probe radiation to split into pulses with different polarization characteristics. If the input probe radiation is weak enough, these pulses have constant polarization characteristics and are normal mode pulses. In the case of a higher power of the input probe radiation, the pulses into which it splits in the medium are not normal mode pulses, but their polarization characteristics fluctuate near the values inherent in normal modes. At the same time, the phase modulation of the probe field is present at all stages of its propagation in the medium. It has been shown that the transparency of the medium for the probe field decreases with increasing intensity of the input probe radiation. However, it is sufficiently large if the polarization characteristics of the input probe radiation coincide with those for the normal mode, the major axis of the polarization ellipse of which is parallel to the major axis of the control field polarization ellipse.