| 1. |
- Hellström, Jonas, et al.
(author)
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Efficient Yb : KGW lasers end-pumped by high-power diode bars
- 2006
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In: Applied physics. B, Lasers and optics (Print). - : Springer Science and Business Media LLC. - 0946-2171 .- 1432-0649. ; 82:2, s. 235-239
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Journal article (peer-reviewed)abstract
- The laser performance of Yb:KGW under end-pumping with high-power diode bars has been investigated. In one configuration, the pump is delivered through an optical fiber yielding a symmetric but unpolarized pump spot. In the second configuration, the pump is delivered through an optical lens system yielding a polarized but asymmetric pump spot. Both configurations resulted in a maximum optical to optical efficiency of 47% and a maximum power of 12.4 W has been generated with the fiber coupled pump source. The output power was limited by crystal fracture, which occurred at an estimated temperature gradient of 1.2 x 10(5) K/m. Thermal lensing and laser tuning characteristics are also investigated.
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| 2. |
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| 3. |
- Loiko, Pavel, et al.
(author)
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Inkjet-printing of graphene saturable absorbers for similar to 2 mu m bulk and waveguide lasers
- 2018
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In: Optical Materials Express. - : Optical Society of America. - 2159-3930 .- 2159-3930. ; 8:9, s. 2803-2814
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Journal article (peer-reviewed)abstract
- A technique for inkjet-printing of graphene saturable absorbers (SAs) for similar to 2-mu m bulk and waveguide lasers is presented. Based on distillation-assisted solvent exchange to fabricate high-concentration graphene inks, this technique is capable of producing few-layer graphene films of arbitrary shape. Absorption saturation of graphene printed on glass is demonstrated at similar to 1.56 mu m for picosecond and femtosecond pulses indicating a large fraction of the saturable losses. Inkjet-printed transmission-type graphene SAs are applied in passively Q-switched nanosecond thulium (Tm) microchip and planar waveguide lasers. The Tm microchip laser generates 136 ns / 1.2 mu J pulses at 1917 nm with a repetition rate of 0.37 MHz with a Q-switching conversion efficiency reaching 65%. The planar waveguide laser generates 98 ns / 21 nJ pulses at 1834 nm at a repetition rate in the MHz-range. The inkjet-printing technique is promising for production of patterned SAs for waveguide lasers.
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| 4. |
- Loiko, Pavel, et al.
(author)
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Oriented zinc oxide nanorods : A novel saturable absorber for lasers in the near-infrared
- 2018
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In: Beilstein Journal of Nanotechnology. - : Beilstein Institut. - 2190-4286. ; 9, s. 2730-2740
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Journal article (peer-reviewed)abstract
- Zinc oxide (ZnO) nanorods (NRs) oriented along the crystallographic [001] axis are grown by the hydrothermal method on glass substrates. The ZnO NRs exhibit a broadband (1-2 mu m) near-IR absorption ascribed to the singly charged zinc vacancy V-z(n)-1. The saturable absorption of the ZnO NRs is studied at approximate to 1 mu m under picosecond excitation, revealing a low saturation intensity, approximate to 10 kW/cm(2), and high fraction of the saturable losses. The ZnO NRs are applied as saturable absorbers in diode-pumped Yb (approximate to 1.03 mu m) and Tm (approximate to 1.94 mu m) lasers generating nanosecond pulses. The ZnO NRs grown on various optical surfaces are promising broadband saturable absorbers for nanosecond near-IR lasers in bulk and waveguide geometries.
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| 5. |
- Seger, Kai, 1981-
(author)
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Compact solid-state lasers in the near-infrard and visible spectral range
- 2013
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Doctoral thesis (other academic/artistic)abstract
- The subject of this thesis is the exploration of new concepts for compact solid-state lasers in the visible and near-infrared spectral range using new components such as volume Bragg gratings for wavelength stabilisation and wavelength tuning. Also single-walled carbon nanotubes for mode-locking and Q-switching of lasers have been studied.We have developed a new method for the tuning of solid-state lasers by replacing a dielectric mirror with a transversally chirped volume Bragg grating, which allows smooth wavelength tuning without additional elements inside the laser cavity. The result is a more compact laser, since the tuning mechanism and output coupler are incorporated in one component. Another benefit is an increased efficiency, since additional elements inside the cavity will always add to the total loss of the laser. This has been demonstrated for a broadband ytterbium laser around 1 µm and a single-longitudinal-mode Nd:YVO4 laser around 1.06 µm. A volume Bragg grating has also been used to construct an efficient, narrow-linewidth ytterbium fiber laser and the employment of a volume Bragg gratingas the pump mirror of a solid-state laser for frequency-doubling has been investigated. Both lasers represent a practical solution, eliminating the use of additional intracavity elements.Second-harmonic generation is an efficient way to access the visible spectral range using diode-pumped solid-state lasers. However, these lasers can suffer from large amplitude fluctuations, which has been analyzed in more detail for an optically-pumped semiconductor disk-laser and a volume Bragg grating locked ytterbiumlaser. The control of those amplitude fluctuations is very important, since many applications like fluorescence microscopy require a laser with a constant output power and as little noise as possible.In addition to this, we have demonstrated, that saturable absorbers based on quan-tum dots and carbon nanotubes can be used to mode-lock compact laser at a wavelength around 1.03 µm. Those lasers have many interesting applications incommunications, clock generation, metrology and life sciences.
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