Optical response and surface morphology of crystalline Nd3+-doped fluoride films grown on monocrystalline LiYF4 substrates by pulsed laser deposition

The realization of crystalline films of Nd3+:YF3 and Nd3+:LiYF4 on a monocrystalline LiYF4 substrate by pulsed laser deposition is reported. The films were obtained by laser ablation with 355 nm photons of a bulk LiYF4 crystal doped with Nd3+ ions at 1.5% atomic concentration in the presence of different ablation/deposition parameters. The films optical characteristics, analyzed via laser induced polarized fluorescence spectroscopy upon IR excitation, are presented. Lifetime measurements of the fundamental Nd3+ ion transition in the film were also performed. All these results were compared with those obtained in the Nd3+:LiYF4 bulk crystal. The surface morphology of the depositions was analyzed via a scanning electron microscope. When the production of the deposition took place in high vacuum (1 × 10− 4 Pa) and the substrate temperature was 750 °C, the grown film was Nd3+:YF3. A 1 Pa controlled atmosphere of He in the ablation chamber and a substrate temperature of 650 °C favoured the growth of a Nd3+:LiYF4 film. In the latter case the film showed also a smoother surface.