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We report on a high-power Ho:YAG single-crystal fiber (SCF) laser inband pumped by a high-brightness Tm-fiber laser at 1908 nm. The Ho:YAG SCF grown by the micro-pulling-down technique exhibits a propagation loss of $0.05\pm 0.005~\text{cm}^{-1}$ at $2.09~\unicode[STIX]{x03BC}\text{m}$. A continuous-wave output power of 35.2 W is achieved with a slope efficiency of 42.7%, which is to the best of our knowledge the highest power ever reported from an SCF-based laser in the 2 $\unicode[STIX]{x03BC}\text{m}$ spectral range. [ABSTRACT FROM AUTHOR]

We report on the growth and laser operation of Tm:Lu3Al5O12 (Tm:LuAG) single crystal grown via the micro-pulling-down ($\mu $ -PD) method, for the first time to the best of our knowledge. Spectral properties (absorption and fluorescence) and fluorescence lifetime of the Tm:LuAG crystal were measured at room temperature. Using a 790-nm diode laser as pump source, continuous-wave laser operation of the Tm:LuAG crystal was demonstrated with a maximum output power of 2.88 W and a slope efficiency of about 39.1% at 2016 nm. Passively $Q$ -switched laser operation was also investigated using Cr:ZnSe as saturable absorber. The maximum average output power reached about 0.53 W with the shortest pulse width of 54.3 ns and a pulse energy of $21.9~\mu \text{J}$. This letter reveals that the $\mu $ -PD technique is reliable for growing high-performance Tm3+-doped crystals for various potential applications. [ABSTRACT FROM AUTHOR]

We report on a femtosecond semiconductor saturable absorber mirror (SESAM) mode-locked Yb:LuYAG laser. Pumped by a 976 nm single-mode fiber laser, a self-starting mode-locked Yb:LuYAG laser was demonstrated, delivering a 618-mW output power with 140-fs pulses and a 95.4-MHz repetition rate. The output spectrum is centered at 1053 nm with a spectral width of 10.4 nm. To the best of our knowledge, this is the shortest pulse ever generated from a mode-locked Yb:LuYAG laser. [ABSTRACT FROM AUTHOR]

BGO single crystals doped with Er3+, Tm3+ and Ho3+ rare-earth ions were prepared in the form of rod-type crystal fibers via the micro-pulling down technique to perform an extensive investigation of their visible, near- and mid-infrared luminescence properties and to really decide on their interest as solid-state laser media in the various spectral domains. Revisiting and completing the absorption spectra already available in the literature led to the derivation of more reliable "effective" radiative lifetimes and branching ratios. Registration of the fluorescence decays of the most important emitting levels versus dopant concentrations led for the first time to an unambiguous determination of "intrinsic" emission lifetimes – corresponding to negligible contributions from inter-ionic energy-transfers - and non-radiative multiphonon relaxation rates. Such data also allowed for the determination of the dominant phonon energy which comes into play in the electron-phonon coupling responsible for these multiphonon relaxation processes and for its lattice vibration origin, i.e. a high phonon energy of the order of 820 cm−1 corresponding to the coupling between bending vibrations of (GeO 4)4- tetrahedra and vibrations corresponding to motions of these (GeO 4)4- tetrahedra against the Bi3+ ions for which the rare-earth dopant ions substitute. Using the above data and different methods for the calibration of the registered emission spectra in cross section unit and for the derivation of gain cross section curves finally show that mid-infrared emissions of Er:BGO, Tm:BGO and Ho:BGO around 1.55 μm, 1.9 μm and 2 μm, respectively, occur with comparable gain cross sections as in the most important reference mid-infrared laser materials, although over slightly shifted thus complementary spectral domains. It is shown that potentialities also exist with Tm:BGO in the blue, deep-red and near-infrared spectral domains around 470 nm, 800 nm and 1.45 μm, by pumping the crystals with conventional pump sources and using some suitable co-dopants to avoid detrimental self-terminating processes. • Bi 4 Ge 3 O 12 rod-type crystal fibers doped with Er3+, Tm3+ and Ho3+ ions are successfully grown by using the micro-pulling down technique. • An extensive spectroscopic investigation is performed from the near-UV to the mid-infrared. • Effective radiative and intrinsic emission lifetimes are unambiguously determined for all the important emitting levels. • The origin and the energy of the phonons responsible for the non-radiative multiphonon relaxation of the emitting levels are clearly identified. • Emission and gain cross section spectra show the interest of Er3+, Tm3+ and Ho3+ doped BGO crystals for the high power mid-infrared laser application. [ABSTRACT FROM AUTHOR]