title: Thermal characterization, crystal field analysis and in-band pumped laser performance of Er doped NaY(WO(4))(2) disordered laser crystals.
abstract: Undoped and Er-doped NaY(WO4)2 disordered single crystals have been grown by the Czochralski technique. The specific heat and thermal conductivity (κ) of these crystals have been characterized from T = 4 K to 700 K and 360 K, respectively. It is shown that κ exhibits anisotropy characteristic of single crystals as well as a κ(T) behavior observed in glasses, with a saturation mean free phonon path of 3.6 Å and 4.5 Å for propagation along a and c crystal axes, respectively. The relative energy positions and irreducible representations of Stark Er(3+) levels up to (4)G(7/2) multiplet have been determined by the combination of experimental low (<10 K) temperature optical absorption and photoluminescence measurements and simulations with a single-electron Hamiltonian including both free-ion and crystal field interactions. Absorption, emission and gain cross sections of the (4)I(13/2)↔(4)I(15/2) laser related transition have been determined at 77 K. The (4)I(13/2) Er(3+) lifetime (τ) was measured in the temperature range of 77-300 K, and was found to change from τ (77K) ≈ 4.5 ms to τ (300K) ≈ 3.5 ms. Laser operation is demonstrated at 77 K and 300 K by resonantly pumping the (4)I(13/2) multiplet at λ≈1500 nm with a broadband (FWHM≈20 nm) diode laser source perfectly matching the 77 K crystal (4)I(15/2) → (4)I(13/2) absorption profile. At 77 K as much as 5.5 W of output power were obtained in π-polarized configuration with a slope efficiency versus absorbed pump power of 57%, the free running laser wavelength in air was λ≈1611 nm with the laser output bandwidth of 3.5 nm. The laser emission was tunable over 30.7 nm, from 1590.7 nm to 1621.4 nm, for the same π-polarized configuration.
authors.affiliation: Department of Photonic Materials, Instituto de Ciencia de Materiales de Madrid, Consejo Superior de Investigaciones Científicas, Madrid, Spain.
authors.forename: María Dolores
authors.initials: MD
authors.lastname: Serrano
authors.forename: Concepción
authors.initials: C
authors.lastname: Cascales
authors.forename: Xiumei
authors.initials: X
authors.lastname: Han
authors.forename: Carlos
authors.initials: C
authors.lastname: Zaldo
authors.forename: Andrzej
authors.initials: A
authors.lastname: Jezowski
authors.forename: Piotr
authors.initials: P
authors.lastname: Stachowiak
authors.forename: Nikolay
authors.initials: N
authors.lastname: Ter-Gabrielyan
authors.forename: Viktor
authors.initials: V
authors.lastname: Fromzel
authors.forename: Mark
authors.initials: M
authors.lastname: Dubinskii
mesh_terms: D003460:Crystallization; D004867:Equipment Design; D006358:Hot Temperature; D053844:Lasers, Solid-State; D008027:Light; D013696:Temperature; D013814:Thermal Conductivity
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