Vacuum Deposited Erbium-Doped NIR Luminescent Organic Thin Films For 1.5 μm Optical Amplification Applications

Abstract

AbstractInorganic erbium-doped glasses are widely used in telecommunications due to the sharp intra-atomic 4I13/2 → 4I15/2 transition in the 4f orbital of erbium resulting in an emission at ∼ 1.5 μm, which is the low loss window of silica optical fibres. The limited erbium concentration of about 1020 ions.cm−3 in inorganic erbium-doped glasses and the low absorption coefficient of the Er3+ ions, imply that relatively long lengths of fibre are required. The organic erbium complexes present higher absorption cross sections due to the photosensitization of erbium by organic conjugated ligands and broader emission bands than those of the free Er3+ ion. Such properties open the possibility to develop compact, low power and broadband infrared emitting devices. We present the study of a highly doped organic thin film obtained from organic erbium complexes deposited by a vacuum sublimation technique. This deposition method allows the realization of an erbium-doped thin film without the help of an organic polymer matrix, which is a potential source of vibrationnal luminescence quenching. The ligands used in the present study are fluorinated in order to limit the vibrationnal quenching of the ligand itself, and to increase the volatility of the complexes. In this paper, we report the synthesis, the sublimation process and the characterization of the thin films.