Electromagnetically induced transparency in acetylene molecules with counterpropagating beams in V and Λ schemes

We report on the experimental observation of electromagnetically induced transparency in V and Lambda energy level schemes using counterpropagating coupling and probe beam geometry. The observation was achieved using an acetylene photonic microcell. The conditions required for this observation are explored theoretically, and we show that the use of counterpropagating beams in electromagnetically induced transparency may have applications as a spectroscopic technique where velocity discrimination is desirable.