Intermode Correlation Properties of Laser Radiation Propagating through a Gas Cell with Alkali Atoms under Conditions of a Coherent Population Trapping Resonance

A theory of excitation of a coherent population trapping resonance in hot alkali-metal atoms in a cell with buffer gas is constructed, taking into account the finite spectral width of two-component radiation, its vector properties, and the hyperfine and Zeeman structures of atoms. The propagation of intermode correlations in an optically dense gas cell is studied. It is found that in the case of partially correlated input modes, their correlation degree at the output can increase. This effect can be used for filtering the incoherent part of radiation.