Optical waveguide based on amorphous Er3+-doped Ga–Ge–Sb–S(Se) pulsed laser deposited thin films

Amorphous chalcogenide films play a motivating role in the development of integrated planar optical circuits due to their potential functionality in near infrared (IR) and mid-IR spectral regions. More specifically, the photoluminescence of rare earth ions in amorphous chalcogenide films can be used in laser and amplifier devices in the IR spectral domain. The aim of the present investigation was to optimize the deposition conditions for the fabrication of undoped and Er3+ doped sulphide and selenide thin films with nominal composition Ga5Ge20Sb10S(Se)65 or Ga5Ge23Sb5S67 by pulsed laser deposition (PLD). The study of compositional, morphological and structural characteristics of the layers was realized by scanning electron microscopy-energy dispersive spectroscopy, atomic force microscopy and Raman spectroscopy analyses, respectively. Some optical properties (transmittance, index of refraction, optical band gap, etc.) of prepared chalcogenide films and optical losses were investigated as well. The clear identification of near-IR photoluminescence of Er3+ ions was obtained for both selenide and sulphide films. The decay of the 4I13/2 → 4I15/2 transition at 1.54 µm in Er3+ doped Ga5Ge20Sb10S65 PLD sulphide films was studied to assess the effects of film thickness, rare earth concentration and multilayer PLD deposition on their spectroscopic properties.