Identification of Λ-like systems in Er3+:Y2SiO5 and observation of electromagnetically induced transparency

Electromagnetically induced transparency (EIT) is reported in a solid-state material doped with erbium ions. In this paper we introduce the spectroscopic investigations we have conducted in order to identify the adequate Lambda-like three-level systems in Er3+:Y2SiO5 crystal, relevant for the demonstration of EIT. These results pave the way for nonlinear and quantum optics applications based on EIT at the telecom wavelength around 1.5 mu m.