We demonstrated a 967 nm diode end-pumped Er:GSGG laser operated at 2.794 Micrometer with spectrum width 3.6 nm in the continuous wave(CW) mode. The maximum output power of 440 mW is obtained at an incident pumping power of 3.4 W, which corresponds t
o an optical-to-optical efficiency of 13% and slope efficiency of 13.2%. The results suggest that short cavity and efficient cooling setup for crystal are advantageous to improve laser performance.
We present a detailed temperature dependent Raman light scattering study of optical phonons in Ba{1-x}K{x}Fe{2}As{2} (x ~ 0.28, superconducting Tc ~ 29 K), Sr{1-x}K{x}Fe{2}As{2} (x ~ 0.15, Tc ~ 29 K) and non-superconducting BaFe{2}As{2} single crysta
ls. In all samples we observe a strong continuous narrowing of the Raman-active Fe and As vibrations upon cooling below the spin-density-wave transition Ts. We attribute this effect to the opening of the spin-density-wave gap. The electron-phonon linewidths inferred from these data greatly exceed the predictions of ab-initio density functional calculations without spin polarization, which may imply that local magnetic moments survive well above Ts. A first-order structural transition accompanying the spin-density-wave transition induces discontinuous jumps in the phonon frequencies. These anomalies are increasingly suppressed for higher potassium concentrations. We also observe subtle phonon anomalies at the superconducting transition temperature Tc, with a behavior qualitatively similar to that in the cuprate superconductors.
