Abstract

We propose the effective and easy method for controlling a sign of narrow resonances of electromagnetically-induced transparency (EIT, [1,2]) and absorption (EIA, [3]). These nonlinear resonances are the bright examples of the nonlinear effects based on the low-frequency atomic coherences. The former effect is connected with the phenomenon of the coherent population trapping (CPT, [4]), while the latter is described by the spontaneous coherence transfer from excited state to ground one [5]. Widths of the EIA and EIT signals can be much less than the natural width. Therefore, they are often called subnatural resonances. EIT and EIA have already found numerous applications in nonlinear optics (e.g., four-wave mixing), optical communications (so-called “slow” and “fast” light), metrology (miniature atomic clocks and magnetometers), laser physics and so on.

© 2011 IEEE