Chirped pulse propagation influenced by coherent population trapping in molecular media

We study the excitation of the quantum coherence in a $\\Lambda$-type molecular media and its influence on chirped pulse propagation. The coherent population trapping (CPT) of the ground states in the $\\Lambda$-system results in fascinating new dynamics of pulse propagation through it. We have considered the two- and three-level molecules. The dressed state basis approach is employed, which provides deep physical insights showing interaction of “bright” and “dark” states with radiation. The level structure of the model is common for the molecular media, where the ground states maybe the ro-vibrational levels of the ground electronic state. We consider a gas of three-level atoms or molecules in the presence of two coherent optical pulses. We demonstrate the importance of role of the dark states. The presented results are important for applications to manipulation of quantum states for molecular detection in engineering, chemical, and biological applications.