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The development of novel crystals with low-phonon-energies continues to be an active area of research for laser applications in the mid-infrared (MIR) region [1-3]. In this work, the material purification, synthesis, crystal growth, and spectroscopic characterization of Pr3+ doped ternary lead halides including Pr: TlPb2Br5 (Pr: TPB), Pr: KPb2Br5 (Pr: KPB), and Pr: CsPbCl3 will be presented. The synthesis of the studied materials was based on the purification of commercial starting materials including directional freezing, multi-pass translation in a zone-melting system and halogenation. The growth of the purified materials was then carried out through vertical Bridgman technique using a two-zone furnace. The trivalent praseodymium ion (Pr3+) offers several intra-4f transitions of interest for laser applications. Using the output of a ~1.5 m fiber laser as excitation source, IR emissions centered at ~1.6 m (3F4/3F33H4) ~2.4 m (3F2/3H63H4), and ~4.6 μm (3H53H4) were observed from all samples at room-temperature. The decay-times of the two bromide crystals Pr: TPB and Pr: KPB were in the millisecond range, whereas Pr: CsPbCl3 exhibited a significantly shorter lifetime of only ~20 s at room-temperature. The short MIR emission lifetime of Pr: CsPbCl3 indicates strong emission quenching, which is most likely through a combination of multi-phonon-relaxation and impurity related quenching mechanism.
Reference
[1] S. R. Bowman, J. Ganem, B. J. Feldman, and A. W. Kueny, J. Ganem, "Infrared Laser Characteristics of Praseodymium-Doped Lanthum Trichloride", IEEE J. Quant. Electron. 30, (1994) 2925.
[2] N. Ter-Gabrielyan, T. Sanamyan, and M. Dubinskii, “Resonantly pumped Pr3+-doped eye-safe laser at ~1.65µm" Opt. Lett. 34 (2009) 1949.
[3] B. M. Walsh, U. Hommerich, A. Yoshikawa, A. "Toncelli, Mid-infrared spectroscopy of Pr-doped materials", Journal of Luminescence 197 (2018) 349.
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