ELECTROMAGNETICALLY INDUCED TRANSPARENCY IN A SODIUM VAPOR CELL

The report on an investigation of electromagnetically induced transpar ency (EIT) in sodium vapour. In our experiment, sodium atoms are excit ed on the D-1-line with laser radiation containing two components with a frequency difference close to that of the two hyperfine ground stat es of sodium (1.772 GHz). Such an excitation leads to coherent trappin g of atomic population in ''dark'' superpositional states, which drama tically reduces the absorption of light. A frequency transparency wind ow is measured to have a subnatural width, which is a clear indication of coherent population trapping. Dependence of EIT on laser frequenci es and intensities, on the magnetic field strength as well as on the t emperature of the sodium vapour is studied.