| 1. |
- Bertani, Stefano, et al.
(author)
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Stretching-tunable external-cavity laser locked by an elastic silicone grating
- 2006
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In: Optics Express. - 1094-4087. ; 14:25, s. 11982-11986
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Journal article (peer-reviewed)abstract
- We demonstrate wavelength locking of a diode laser at 760 nm with feedback from an elastic transmission grating in the Littrow configuration. The laser was in a single longitudinal mode with a side-mode suppression of 20 dB. By stretching the grating the laser could be tuned over a few nm. The grating was fabricated in a silicone elastomer ( polydimethylsiloxane) by a moulding technique, and coated by a thin layer of Ti and Au to achieve an increased diffraction efficiency needed for efficient locking.
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| 2. |
- Bjurshagen, Stefan, et al.
(author)
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946-nm Nd : YAG laser under ground-state direct diode-pumping at 869 nm
- 2005
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In: 2005 Conference on Lasers & Electro-Optics (CLEO), Vols 1-3. - WASHINGTON, DC : OPTICAL SOC AMERICA. - 1557527954 ; , s. 328-330
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Conference paper (peer-reviewed)abstract
- We have demonstrated, what we believe is for the first time, direct diode-pumping at 869 rim into the emitting level of a quasi-three-level Nd:YAG laser operating at 946 nm.
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| 3. |
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| 4. |
- Bjurshagen, Stefan, 1975-
(author)
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Diode-pumped rare-earth-doped quasi-three-level lasers
- 2005
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Doctoral thesis (other academic/artistic)abstract
- Many rare-earth-doped materials are suitable for laser operation and this thesis focuses on diode-pumped solid-state lasers employing crystals doped with the trivalent rare-earth ions neodymium (Nd3+), ytterbium (Yb3+) and erbium (Er3+). Especially, the quasi-three-level transitions in Nd and Yb have been studied as well as the eye-safe three-level transition around 1.5 µm in Er. Quasi-three-level laser transitions in neodymium-doped crystals such as Nd:YAG, Nd:YLF and Nd:YVO4 have received a great deal of interest because they allow for generation of blue light by frequency doubling. For solid-state blue laser sources, there exist numerous applications as in high-density optical data storage, colour displays, submarine communication and biological applications. Efficient lasing on quasi-three-level transitions at 900¬–950 nm in Nd-doped crystals is considerably more difficult to achieve than on the stronger four-level transitions at 1–1.1 µm. The problems with these quasi-three-level transitions are a significant reabsorption loss at room temperature and a small stimulated emission cross section. This requires a tight focusing of the pump light, which is achieved by end-pumping with high-intensity diode lasers. Nd:YAG lasers at the 946 nm transition have been built and a maximum power of 7.0 W was obtained. By inserting a thin quartz etalon in the laser cavity, the 938.5 nm laser line could be selected and an output power of 3.9 W was then obtained. By using nonlinear crystals, frequency-doubling of laser light at both 946 nm and 938.5 nm was achieved. Efficient generation of blue light at 473 nm has been obtained in periodically poled KTP, both in single-pass extra-cavity and intracavity configurations. More than 0.5 W was obtained at 473 nm by intracavity doubling. Intracavity second harmonic generation of the 938.5 nm transition gave slightly more than 200 mW at 469 nm. During recent years, Yb-doped double-tungstate crystals like KGW and KYW have shown efficient laser operation. A comparative, experimental study of the laser performance and thermal-lensing properties between standard b-cut Yb:KGW and Yb:KGW cut along a novel athermal direction is presented. The results show that the thermal lens is about two times weaker and less astigmatic in the athermal-direction-cut crystal, for the same absorbed power. Also, Er-Yb-doped KGW and KYW have been investigated and the fluorescence dynamics have been measured for the Yb (2F5/2), Er (4I13/2) and Er (4S3/2) levels around 1 µm, 1.5 µm and 0.55 µm, respectively. The influence of upconversion is a detrimental effect both in Nd-doped and Er-Yb-doped lasers. Analytical models starting from rate equations have been developed for these lasers including the influence of upconversion effects. The results of the general models have been applied to 946 nm Nd:YAG lasers and to Er-Yb-doped double-tungstate crystals in order to find the optimum doping concentrations for high gain for an eye-safe laser at 1.53 µm.
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| 5. |
- Bjurshagen, Stefan, et al.
(author)
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Quasi-three-level Nd:YAG laser under diode pumping directly into the emitting level
- 2006
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In: Optics Communications. - : Elsevier BV. - 0030-4018 .- 1873-0310. ; 261:1, s. 109-113
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Journal article (peer-reviewed)abstract
- We present theoretical and experimental investigations on ground-state direct pumping at 869 nm into the emitting level F-4(3/2) of end-pumped quasi-three-level Nd:YAG lasers operating at 946 nm. We have demonstrated, what we believe is for the first time, a Nd:YAG laser at 946 nm directly pumped by diodes and obtained 1.6 W of output power.
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| 6. |
- Campbell, S., et al.
(author)
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Frequency-doubling in femtosecond laser inscribed periodically-poled potassium titanyl phosphate waveguides
- 2007
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In: Optics Express. - 1094-4087. ; 15:25, s. 17146-17150
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Journal article (peer-reviewed)abstract
- Frequency doubling has been achieved in femtosecond-laser-inscribed single-mode waveguides written in two periodically-poled potassium titanyl phosphate crystals. A conversion efficiency of 0.22 %W-1 was obtained for first-order quasi-phase matching at 980 nm and an efficiency of 0.02 %W-1 for third-order quasi-phase matching at 800 nm.
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| 7. |
- Campbell, S., et al.
(author)
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Frequency doubling in femtosecond-written periodically-poled potassium titanyl phosphate waveguides
- 2007
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In: Lasers and Electro-Optics, 2007 European Conference on and the International Quantum Electronics Conference. - 1424409306 - 9781424409303 ; , s. 4386106-
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Conference paper (peer-reviewed)abstract
- The second-harmonic conversion efficiency within the PPKTP waveguide is investigated using two separate tunable CW Ti:sapphire lasers at 800 nm and 980 nm. Results show strong conversion efficiency which imply that the local damage-induced index modification does not adversely affect the periodic domain structure in the material.
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| 8. |
- Campbell, S., et al.
(author)
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Frequency doubling in femtosecond-written periodically-poled potassium titanyl phosphate waveguides
- 2007
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In: Conference on Lasers and Electro-Optics, 2007, CLEO 2007. - 9781557528346 ; , s. 4452462-
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Conference paper (peer-reviewed)abstract
- Frequency doubling is demonstrated in femtosecond-laser-created single-mode waveguides written in a periodically-poled potassium titanyl phosphate crystal. Conversion efficiencies of 0.22%/W (0.02%/W) were obtained for first (third) order phasematching at 980nm (800nm).
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| 9. |
- Canalias, Carlota, et al.
(author)
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A KTiOPO4 nonlinear photonic crystal for blue second harmonic generation
- 2009
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In: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 94:8
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Journal article (peer-reviewed)abstract
- A nonlinear photonic crystal with a rectangular domain lattice of 6.09x6 mu m(2) has been fabricated and characterized in flux-grown KTiOPO4. It was used to demonstrate continuous-wave and multiple beam tunable blue second harmonic generation.
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| 10. |
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