Analysis of High Efficiency Electromagnetically Induced Transparency in Potassium Vapor

We present a rate-equation theoretical model describing the optical pumping processes on the K D1 line and we then discuss their influence on the electromagnetically induced transparency resonance parameters. We present also a comparison with the results of an experiment performed in cells containing pure alkali metal or added with a few torrs of buffer gas. The model shows that, in the last case, the complete Maxwellisation of the atomic population velocity distribution, along with the overlapping Doppler profiles of the transitions from the ground-states typical of K, leads to a partial compensation of optical pumping and a significant increase of the amplitude of the electromagnetically induced transparency resonances.