New Monocrystals with Low Phonon Energy for Mid-IR Lasers
Various aspects of crystal growth, structure, physical and optical properties of new low phonon energy crystals, namely the rare earth doped alkali-lead halide crystals RE3+: MPb2Hal5(M = Rb, K and Hal = Cl, Br), are described. The crystals were grown using the Bridgman technique, most of crystals were grown for the first time. The results of spectroscopic study of the RE3+-doped double chloride crystals, RE3+:KPb2Cl5 (RE3+ = Pr3+, Nd3+, Tb3+, Dy3+, Ho3+, Er3+, Yb3+), and new double bromide KPb2Br5 and RbPb2Br5 crystals doped with Nd3+ and Tb3+ are presented, including multiphonon non-radiative relaxation rates, and absorption and emission spectra. Judd-Ofelt intensity parameters, as well as radiative transition probabilities, lifetimes, and branching ratios are summarized. The efficiency of up-conversion is demonstrated in Nd and Er doped KPb2Cl5crystals. The luminescence dynamics and energy transfer processes responsible for population of excited RE3+ levels and laser action are discussed. The possibility of laser action in the mid-infrared is considered.
Keywords: Double alkali-lead halides, crystal growth, phase transitions, crystal structure, optical properties, rare earth ions, optical spectra, phonon spectrum, absorption cross section, energy transfer, upconversion, multiphonon relaxation, population dynamics, laser action.
KeywordsPhonon Energy Excited State Absorption Upconversion Luminescence Upconversion Emission Ground State Absorption
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