The electromagnetically induced transparency in a @sV-shaped atomic system is observed by a spectroscopy technique. The experimental results show that the absorption coefficient at maximum coherence is reduced by about 72% of the maximum absorption ${\mathrm{\alpha }}_0$, which is the case without the coherent effect. Meanwhile we also observed indirectly population trapping in the two excited states, which means that there is no decay via spontaneous or stimulated emission to the lower state. © 1996 The American Physical Society.

• Received 22 May 1995

DOI:https://doi.org/10.1103/PhysRevA.53.1160