Anders Larsson - Academia.edu (original) (raw)
Papers by Anders Larsson
Paper artefacts are considered invaluable in many work settings and they are often used for overv... more Paper artefacts are considered invaluable in many work settings and they are often used for overview in collaboration. In such cases, augmenting paper with computer power can be a suitable approach to gain digital benefits while still keeping the paper-based practices. However, augmenting paper introduces new physical and digital challenges, both for the designers and the users. We have compared two different research systems that augment paper and discuss emerging design challenges on augmented paper approaches.
Optics Letters, 2000
A compact integration-compatible semiconductor laser supporting a planar Gaussian mode is demonst... more A compact integration-compatible semiconductor laser supporting a planar Gaussian mode is demonstrated. Curved deep-etched distributed Bragg ref lectors (DBR's), contouring the phase front of the Gaussian wave, act as feedback elements. The DBR's are 0.5 mm deep and have two f irst-order air gaps separated by a third-order semiconductor spacer. Low-threshold current (10 mA) is achieved for a 90-mm-long laser with a waist of 2 mm. Lasing in a planar Gaussian mode is observed up to 1.7 times the threshold current, whereas at higher currents the mode behavior degrades because of spatial hole burning.
A link employing a 7 µm oxide aperture VCSEL and a 30 GHz photoreceiver with an integrated limiti... more A link employing a 7 µm oxide aperture VCSEL and a 30 GHz photoreceiver with an integrated limiting amplifier enabled error-free transmission up to [2]: 47 Gbit/s back-to-back (BTB) at room temperature (RT) 44 Gbit/s over 50 m OM4 fiber at room temperature 40 Gbit/s back-to-back at temperatures up to 85°C.
ABSTRACT We have studied the modulation bandwidth of high-speed GaInNAs double-quantum-well laser... more ABSTRACT We have studied the modulation bandwidth of high-speed GaInNAs double-quantum-well lasers emitting at 1.28–1.30 μm. A 400 μm long ridge waveguide laser exhibits a small signal modulation bandwidth of 14 GHz. The intrinsic damping limited modulation bandwidth is as high as 25 GHz (K = 0.35 ns), and the actual modulation bandwidth is limited by thermal effects under continuous operation. The saturation of the resonance frequency at 10 GHz was found to be the result of a thermal reduction of the differential gain and a rapid increase of the threshold current when the temperature exceeds 80 °C.
Electronics Letters, 2012
We present results from measurements of the subthreshold lateral spontaneous emission profile in ... more We present results from measurements of the subthreshold lateral spontaneous emission profile in 1.3-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.
New Journal of Physics, 2004
With the rapid development of wireless communication networks there is an increasing demand for e... more With the rapid development of wireless communication networks there is an increasing demand for efficient and cost-effective transmission and distribution of RF signals. Fibre optic RF links, employing directly modulated semiconductor lasers, provide many of the desired characteristics for such distribution systems and in the search for cost-effective solutions, the vertical cavity surface emitting laser (VCSEL) is of interest. It
Acta Obstetricia Et Gynecologica Scandinavica, Oct 1, 2008
... This study was financially supported by the Uppsala University Hospital Research Fund and Eri... more ... This study was financially supported by the Uppsala University Hospital Research Fund and Erik, Karin and Gösta Selander's Foundation. References. ... 3 Marchini G, Berggren V, Djilali-Merzoug R, Hansson LO. The birth process ...
Lakartidningen, Jan 31, 2001
Hypotensive reactions during surgical procedures cause diagnostic problems in establishing whethe... more Hypotensive reactions during surgical procedures cause diagnostic problems in establishing whether the hypotension is due to blood loss or pharmaceuticals or other causes. A case of hypotension probably due to an albumin infusion is described. Bradykinin effects are probably the cause of many hypotensive reactions. Angiotensin-converting enzyme (ACE) inhibitors reduce degradation of bradykinin and thus increase the risk of hypotensive reactions. When possible, doctors should consider withholding ACE inhibitors 24 hours before surgical procedures likely to require albumin transfusions.
Ieee Journal of Quantum Electronics, Sep 1, 2004
We present a comprehensive noise model for verticalcavity surface-emitting lasers (VCSELs). The t... more We present a comprehensive noise model for verticalcavity surface-emitting lasers (VCSELs). The time-domain model accounts for the stochastic fluctuations in the local carrier density in the separate confinement heterostructure and quantum wells, and in the modal intensity and phase of both the internal and the out-coupled optical field. In this work, we consider these fluctuations to be caused by the temporal uncertainty of the processes that supply or consume carriers and photons, such as carrier diffusion and photons escaping the cavity, and the processes that create or annihilate carriers and photons, such as stimulated emission and absorption. The noise model is based on a deterministic quasithree-dimensional dynamic model that treats the carrier transport, heat generation and dissipation, and optical fields in the device. Langevin noise terms are derived and added to the rate equations in the numerical solution. The noise model is applied to simulate the noise characteristics of fundamental-mode stabilized VCSELs with a shallow, mode discriminating, surface relief. The relative intensity noise and frequency noise of the output are calculated. From the latter, the linewidth of the VCSEL can be estimated. The results are compared with those of conventional multimode VCSELs. and is currently working toward the Ph.D. degree. His research is focused on characterizing and modeling the dynamics of vertical-cavity surface-emitting lasers.
Optics Letters, Oct 15, 2005
Passive mode locking of an optically pumped, InP-based, 1550 nm semiconductor disk laser by using... more Passive mode locking of an optically pumped, InP-based, 1550 nm semiconductor disk laser by using a GaInNAs saturable absorber mirror is demonstrated. To reduce material heating and enable high-power operation, a 50 µm thick diamond heat spreader is bonded to the surface of the gain chip. The laser operates at a repetition frequency of 2.97 GHz and emits near-transform-limited 3.2 ps pulses with an average output power of 120 mW.
Http Dx Doi Org 10 1080 09540109809354966, Sep 16, 2008
ABSTRACT Chicken antibodies offer many advantages over the traditional mammalian ones. A laying h... more ABSTRACT Chicken antibodies offer many advantages over the traditional mammalian ones. A laying hen produces large amounts of yolk antibodies and the use of yolk antibodies eliminates the painful procedure of collecting blood from the animal. Thus, the use of chicken antibodies will reduce both the number of animals required to produce antibodies and also animal distress. Chicken antibodies also have several biochemical advantages compared to mammalian antibodies: they often increase the signal and reduce interference in many assays. However, the species chosen for antibody production have usually been mammals. This is probably due to tradition, but also to limited knowledge about the production of chicken antibodies. We studied the immune response in the chicken using small amounts of mammalian antigen, and show that a good immune response can be obtained with 0.1–1.0 μg of bovine serum albumin.
Clinical Chemistry and Laboratory Medicine, Feb 1, 2006
Cystatin C is increasingly used as a glomerular filtration marker, but so far only a few companie... more Cystatin C is increasingly used as a glomerular filtration marker, but so far only a few companies produce most of the cystatin C reagents suited for turbidimetry or nephelometry use in clinical laboratories. We studied different protocols for measuring cystatin C on an Architect ci8200 system using cystatin C reagents from Dako (Glostrup, Denmark). The results were compared with those obtained with Dade Behring reagents (Deerfield, IL, USA) on a BN ProSpec system. Differences in assay protocol on the same instrument with the Dako reagent yielded an up to 50% difference in glomerular filtration rate calculated from the cystatin C results when analyzing patient samples, but had no effect on the results for controls. There were also significant differences regarding linearity and kinetics between samples and controls/calibrators. The results indicate different reactivity of the Dako antibodies against calibrators and controls in comparison with patient samples, highlighting the importance of using controls and calibrators that do not differ from patient samples.
Physica Status Solidi B Basic Solid State Physics, 2011
Circulation, Oct 19, 2004
... Anders Larsson, Petter Westbergh, Johan Gustavsson, ˚Asa Haglund and Benjamin Kögel ... We gr... more ... Anders Larsson, Petter Westbergh, Johan Gustavsson, ˚Asa Haglund and Benjamin Kögel ... We gratefully acknowledge TU Berlin (A Mutig, A Nadtochiy, D Bimberg) for assistance with the 40 Gb s −1 measurements, Tyndall Institute (SB Healy, EP O'Reilly) for the active region ...
Paper artefacts are considered invaluable in many work settings and they are often used for overv... more Paper artefacts are considered invaluable in many work settings and they are often used for overview in collaboration. In such cases, augmenting paper with computer power can be a suitable approach to gain digital benefits while still keeping the paper-based practices. However, augmenting paper introduces new physical and digital challenges, both for the designers and the users. We have compared two different research systems that augment paper and discuss emerging design challenges on augmented paper approaches.
Optics Letters, 2000
A compact integration-compatible semiconductor laser supporting a planar Gaussian mode is demonst... more A compact integration-compatible semiconductor laser supporting a planar Gaussian mode is demonstrated. Curved deep-etched distributed Bragg ref lectors (DBR's), contouring the phase front of the Gaussian wave, act as feedback elements. The DBR's are 0.5 mm deep and have two f irst-order air gaps separated by a third-order semiconductor spacer. Low-threshold current (10 mA) is achieved for a 90-mm-long laser with a waist of 2 mm. Lasing in a planar Gaussian mode is observed up to 1.7 times the threshold current, whereas at higher currents the mode behavior degrades because of spatial hole burning.
A link employing a 7 µm oxide aperture VCSEL and a 30 GHz photoreceiver with an integrated limiti... more A link employing a 7 µm oxide aperture VCSEL and a 30 GHz photoreceiver with an integrated limiting amplifier enabled error-free transmission up to [2]: 47 Gbit/s back-to-back (BTB) at room temperature (RT) 44 Gbit/s over 50 m OM4 fiber at room temperature 40 Gbit/s back-to-back at temperatures up to 85°C.
ABSTRACT We have studied the modulation bandwidth of high-speed GaInNAs double-quantum-well laser... more ABSTRACT We have studied the modulation bandwidth of high-speed GaInNAs double-quantum-well lasers emitting at 1.28–1.30 μm. A 400 μm long ridge waveguide laser exhibits a small signal modulation bandwidth of 14 GHz. The intrinsic damping limited modulation bandwidth is as high as 25 GHz (K = 0.35 ns), and the actual modulation bandwidth is limited by thermal effects under continuous operation. The saturation of the resonance frequency at 10 GHz was found to be the result of a thermal reduction of the differential gain and a rapid increase of the threshold current when the temperature exceeds 80 °C.
Electronics Letters, 2012
We present results from measurements of the subthreshold lateral spontaneous emission profile in ... more We present results from measurements of the subthreshold lateral spontaneous emission profile in 1.3-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.
New Journal of Physics, 2004
With the rapid development of wireless communication networks there is an increasing demand for e... more With the rapid development of wireless communication networks there is an increasing demand for efficient and cost-effective transmission and distribution of RF signals. Fibre optic RF links, employing directly modulated semiconductor lasers, provide many of the desired characteristics for such distribution systems and in the search for cost-effective solutions, the vertical cavity surface emitting laser (VCSEL) is of interest. It
Acta Obstetricia Et Gynecologica Scandinavica, Oct 1, 2008
... This study was financially supported by the Uppsala University Hospital Research Fund and Eri... more ... This study was financially supported by the Uppsala University Hospital Research Fund and Erik, Karin and Gösta Selander's Foundation. References. ... 3 Marchini G, Berggren V, Djilali-Merzoug R, Hansson LO. The birth process ...
Lakartidningen, Jan 31, 2001
Hypotensive reactions during surgical procedures cause diagnostic problems in establishing whethe... more Hypotensive reactions during surgical procedures cause diagnostic problems in establishing whether the hypotension is due to blood loss or pharmaceuticals or other causes. A case of hypotension probably due to an albumin infusion is described. Bradykinin effects are probably the cause of many hypotensive reactions. Angiotensin-converting enzyme (ACE) inhibitors reduce degradation of bradykinin and thus increase the risk of hypotensive reactions. When possible, doctors should consider withholding ACE inhibitors 24 hours before surgical procedures likely to require albumin transfusions.
Ieee Journal of Quantum Electronics, Sep 1, 2004
We present a comprehensive noise model for verticalcavity surface-emitting lasers (VCSELs). The t... more We present a comprehensive noise model for verticalcavity surface-emitting lasers (VCSELs). The time-domain model accounts for the stochastic fluctuations in the local carrier density in the separate confinement heterostructure and quantum wells, and in the modal intensity and phase of both the internal and the out-coupled optical field. In this work, we consider these fluctuations to be caused by the temporal uncertainty of the processes that supply or consume carriers and photons, such as carrier diffusion and photons escaping the cavity, and the processes that create or annihilate carriers and photons, such as stimulated emission and absorption. The noise model is based on a deterministic quasithree-dimensional dynamic model that treats the carrier transport, heat generation and dissipation, and optical fields in the device. Langevin noise terms are derived and added to the rate equations in the numerical solution. The noise model is applied to simulate the noise characteristics of fundamental-mode stabilized VCSELs with a shallow, mode discriminating, surface relief. The relative intensity noise and frequency noise of the output are calculated. From the latter, the linewidth of the VCSEL can be estimated. The results are compared with those of conventional multimode VCSELs. and is currently working toward the Ph.D. degree. His research is focused on characterizing and modeling the dynamics of vertical-cavity surface-emitting lasers.
Optics Letters, Oct 15, 2005
Passive mode locking of an optically pumped, InP-based, 1550 nm semiconductor disk laser by using... more Passive mode locking of an optically pumped, InP-based, 1550 nm semiconductor disk laser by using a GaInNAs saturable absorber mirror is demonstrated. To reduce material heating and enable high-power operation, a 50 µm thick diamond heat spreader is bonded to the surface of the gain chip. The laser operates at a repetition frequency of 2.97 GHz and emits near-transform-limited 3.2 ps pulses with an average output power of 120 mW.
Http Dx Doi Org 10 1080 09540109809354966, Sep 16, 2008
ABSTRACT Chicken antibodies offer many advantages over the traditional mammalian ones. A laying h... more ABSTRACT Chicken antibodies offer many advantages over the traditional mammalian ones. A laying hen produces large amounts of yolk antibodies and the use of yolk antibodies eliminates the painful procedure of collecting blood from the animal. Thus, the use of chicken antibodies will reduce both the number of animals required to produce antibodies and also animal distress. Chicken antibodies also have several biochemical advantages compared to mammalian antibodies: they often increase the signal and reduce interference in many assays. However, the species chosen for antibody production have usually been mammals. This is probably due to tradition, but also to limited knowledge about the production of chicken antibodies. We studied the immune response in the chicken using small amounts of mammalian antigen, and show that a good immune response can be obtained with 0.1–1.0 μg of bovine serum albumin.
Clinical Chemistry and Laboratory Medicine, Feb 1, 2006
Cystatin C is increasingly used as a glomerular filtration marker, but so far only a few companie... more Cystatin C is increasingly used as a glomerular filtration marker, but so far only a few companies produce most of the cystatin C reagents suited for turbidimetry or nephelometry use in clinical laboratories. We studied different protocols for measuring cystatin C on an Architect ci8200 system using cystatin C reagents from Dako (Glostrup, Denmark). The results were compared with those obtained with Dade Behring reagents (Deerfield, IL, USA) on a BN ProSpec system. Differences in assay protocol on the same instrument with the Dako reagent yielded an up to 50% difference in glomerular filtration rate calculated from the cystatin C results when analyzing patient samples, but had no effect on the results for controls. There were also significant differences regarding linearity and kinetics between samples and controls/calibrators. The results indicate different reactivity of the Dako antibodies against calibrators and controls in comparison with patient samples, highlighting the importance of using controls and calibrators that do not differ from patient samples.
Physica Status Solidi B Basic Solid State Physics, 2011
Circulation, Oct 19, 2004
... Anders Larsson, Petter Westbergh, Johan Gustavsson, ˚Asa Haglund and Benjamin Kögel ... We gr... more ... Anders Larsson, Petter Westbergh, Johan Gustavsson, ˚Asa Haglund and Benjamin Kögel ... We gratefully acknowledge TU Berlin (A Mutig, A Nadtochiy, D Bimberg) for assistance with the 40 Gb s −1 measurements, Tyndall Institute (SB Healy, EP O'Reilly) for the active region ...