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- Gustavsson, Johan, 1974, et al.
(author)
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Mode and polarization control in VCSELs using shallow surface structures
- 2007
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In: IET Optoelectronics. ; 1:5, s. 197-205
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Journal article (peer-reviewed)abstract
- Monolithic techniques for mode and polarisation control in vertical-cavity surface emitting lasers (VCSELs) using shallow surface structures are summarized and put in the context with other techniques in terms of performance and manufacturability. The method of using circular-symmetric surface structures for mode control and their combination with a sub-wavelength surface grating for simultaneous mode and polarisation control is described in detail, and adherent experimental results for both 850-nm and 1.3-µm oxide-confined VCSELs are presented.
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- Lind, Lars, et al.
(author)
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Growth-differentiation factor-15 is an independent marker of cardiovascular dysfunction and disease in the elderly : results from the Prospective Investigation of the Vasculature in Uppsala Seniors (PIVUS) Study
- 2009
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In: European Heart Journal. - : Oxford University Press (OUP). - 0195-668X .- 1522-9645. ; 30:19, s. 2346-2353
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Journal article (peer-reviewed)abstract
- AIMS: Growth-differentiation factor-15 (GDF-15) is emerging as an independent prognostic biomarker in patients with cardiovascular (CV) disease. Little is known about the pathophysiological basis for the close association of GDF-15 to future CV events. We hypothesized that GDF-15 is related to underlying CV pathologies. METHODS AND RESULTS: To relate the levels of GDF-15 to indices of CV dysfunction and disease in elderly individuals, serum levels of GDF-15 were measured in 1004 subjects aged 70 years from the Prospective Investigation of the Vasculature in Uppsala Seniors (PIVUS) study. Carotid intima-media thickness and plaque burden, and left ventricular (LV) geometry and function were assessed by ultrasound. Endothelial function was evaluated in forearm resistance vessels and in the brachial artery by venous occlusion plethysmography and ultrasound imaging, respectively. Elevated levels of GDF-15 were related to several CV risk factors (male gender, current smoking, body mass index, waist circumference, diabetes, fasting glucose, triglycerides, and low HDL cholesterol). After adjustment for CV risk factors, increased levels of GDF-15 were associated with reduced endothelium-dependent vasodilation in resistance vessels, plaque burden, LV mass and concentric LV hypertrophy, reduced LV ejection fraction, and clinical manifestations of coronary artery disease and heart failure. CONCLUSION: GDF-15 carries information on CV dysfunction and disease that is not captured by traditional CV risk factors in elderly individuals.
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- Adolfsson, Göran, 1981, et al.
(author)
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Direct observation of lateral carrier diffusion in ridge waveguide InGaNAs lasers
- 2009
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In: IEEE Photonics Technology Letters. - 1041-1135 .- 1941-0174. ; 21:134, s. 134-136
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Journal article (peer-reviewed)abstract
- We present results from measurements of the subthreshold lateral spontaneous emission profile in 1.3-mu m wavelength ridge waveguide InGaNAs quantum-well lasers using a scanning near-field optical microscopy technique. The measurements reveal the presence of significant lateral carrier diffusion which has a profound effect on the temperature dependence of the threshold current. This effect is frequently omitted when the characteristic temperature of the threshold current is considered.
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| 10. |
- Adolfsson, Göran, 1981, et al.
(author)
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Effects of Lateral Diffusion on the Temperature Sensitivity of the Threshold Current for 1.3 um Double Quantum-Well GaInNAs/GaAs Lasers
- 2008
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In: IEEE Journal of Quantum Electronics. ; 44:7, s. 607-616
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Journal article (peer-reviewed)abstract
- We present an experimental and theoretical investigationof the temperature dependence of the threshold current fordouble quantum well GaInNAs–GaAs lasers in the temperaturerange 10 C–110 C. Pulsed measurements of the threshold current have been performed on broad and narrow ridge wave guide(RWG) lasers. The narrow RWG lasers exhibit high characteristic temperatures (T0)of 200 K up to a critical temperature (Tc), above which T0 is reduced by approximately a factor of 2. The T0-values for broad RWG lasers are significantly lower than those for the narrow RWG lasers, with characteristic temperatures on the order of 100 (60) K below (above). Numerical simulations, using a model that accounts for lateral diffusion effects, show good agreement with experimental data and reveal that a weakly temperature dependent lateral diffusion current dominates thethreshold current for narrow RWG lasers.
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