Browsing by Author "Schwoerer, Heinrich"
Now showing 1 - 2 of 2
Results Per Page
Sort Options
- ItemEfficiency of Tm3+ -doped silica triple clad fiber laser(Optical Society of America, 2011) Ndebeka, Wilfrid Innocent; Heidt, A.; Schwoerer, Heinrich; Rohwer, Erich G.We present measurements of the slope efficiency and the pump power at threshold of a Tm3+ -doped silica triple clad fiber laser emitting at 2.02 μm using different cooling techniques. The slope efficiency of 53.6 % was obtained at a temperature of 25oC with a maximum output power of 5 W for 19 W of absorbed power at the pump wavelength of 800 nm and 9.9 W threshold. In a slightly different setup, the output power could be increased to 10 W for an absorbed pump power of 32 W.
- ItemUltrafast dynamics of excitons in tetracene single crystals(AIP Publishing LLC, 2014-03-18) Birech, Zephania; Schwoerer, Markus; Schmeiler, Teresa; Pflaum, Jens; Schwoerer, HeinrichUltrafast exciton dynamics in free standing 200 nm thin tetracene single crystals were studied at room temperature by femtosecond transient absorption spectroscopy in the visible spectral range. The complex spectrally overlapping transient absorption traces of single crystals were systematically deconvoluted. From this, the ultrafast dynamics of the ground, excited, and transition states were identified including singlet exciton fission into two triplet excitons. Fission is generated through both, direct fission of higher singlet states S n on a sub-picosecond timescale, and thermally activated fission of the singlet exciton S 1 on a 40 ps timescale. The high energy Davydov component of the S 1 exciton is proposed to undergo fission on a sub-picoseconds timescale. At high density of triplet excitons their mutual annihilation (triplet-triplet annihilation) occurs on a <10 ps timescale.