Electromagnetically-induced transparency in Doppler-broadened five-level systems

We study electromagnetically-induced transparency (EIT) of a probe field in a Doppler- broadened five-level K-type atomic system driven by three strong laser (coupling) fields. Effect of wave-vector mismatch occurring when the coupling field frequency is higher than that of the probe field frequency (λ _c < λ _p) are considered. Under the influence of the coherent coupling fields, the steady-state linear susceptibility of the probe laser shows that the system can have single or double or triple EIT windows depending on the amplitude and detuning of the coupling fields.