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Papers by Mads Sørensen

Research paper thumbnail of Return-map for semiconductor lasers with optical feedback

1999 IEEE LEOS Annual Meeting Conference Proceedings. LEOS'99. 12th Annual Meeting. IEEE Lasers and Electro-Optics Society 1999 Annual Meeting (Cat. No.99CH37009), 1999

It is well known that a semiconductor laser exposed to moderate optical feedback and biased near ... more It is well known that a semiconductor laser exposed to moderate optical feedback and biased near threshold exhibits the phenomenon of low-frequency intensity fluctuations (LFF). While this behavior can be numerically simulated using the so-called Lang-Kobayshi model, the interpretation of the phenomenon has remained a controversy. The LFF consist of a sudden drop in intensity followed by a build-up in steps of the external cavity roundtrip time, τ, before a new drop-out occurs. The phenomenon has been attributed to a kind of chaotic itinerancy and a bifurcation cascade has been identified very recently. These results give insight into the behavior observed on a short time-scale, but do not explain some of the pronounced features of the LFF seen for moderate feedback levels; namely the stepwise build-up and its characteristic time of about 15 steps close to the solitary laser threshold. We present new results related to the slow time-scale behaviour of LFF which give a simple explanation of these general characteristics, as well as providing a new tool for studying the statistics of the LFF

Research paper thumbnail of Nonlinearity and disorder: Theory and applications. Proceedings of the 5th NATO advanced research workshop (ARW), Tashkent, Uzbekistan, October 2–6, 2001

... Ko'hna dastgoh aylanar hamon Bor olam g'ayb sirini ochib. Xaqiqat shu: hech... more ... Ko'hna dastgoh aylanar hamon Bor olam g'ayb sirini ochib. Xaqiqat shu: hech kim, hech qachon Qutilolmas taqdirdan qochib! Charx quyoshi kezadi jahon Gunoh, savob-ikki dunyodir. ... When God favours one man's soul He opens to him all ways. Mustakim R. Djumaev Page 22. ...

Research paper thumbnail of Fast 2D Simulation of Superconductors: a Multiscale Approach

Research paper thumbnail of Coherent dynamics of excitable and coupled β-cells

Research paper thumbnail of A Course on Applied Superconductivity Shared by Four Departments

Research paper thumbnail of NONLINEAR PROPERTIES OF THE BCS GAP EQUATION

Research paper thumbnail of Quasiperiodic Krönig-Penney Model on a Fibonacci Superlattice

Research paper thumbnail of Numerical Study of Bifurcations in the BCS Gap Equation

Research paper thumbnail of Nonlinear properteis of the BCS gap equation

Research paper thumbnail of Modeling and characterization of colliding pulse mode-locked (CPM) quantum well lasers

Proceedings of SPIE - The International Society for Optical Engineering

ABSTRACT

Research paper thumbnail of Nonlinearity in BCS Models of High-Tc Superconductors

Research paper thumbnail of ELECTROHYDRODYNAMIC STABILITY OF TWO-PHASE MICROFLOWS

Research paper thumbnail of Progress in industrial mathematics at ECMI ’96. Proceedings of the 9th conference of the European Consortium for Mathematics Industry, Lyngby, Denmark, June 1996

Research paper thumbnail of Escape angles in bulk chi((2)) soliton interactions

Research paper thumbnail of Experimental verification of soliton bunching in annular Josephson junction

Research paper thumbnail of Effects of charge-charge interactions and external fields in shape transformations of closed filaments

The role of charge-charge interactions in shape transformations of closed filaments induced by th... more The role of charge-charge interactions in shape transformations of closed filaments induced by the charge-curvature coupling is studied. It is shown that while sufficiently strong repulsive interaction between carriers makes a circular shape of the filament energetically more favorable with a spatially uniform charge distribution along the filament, the attractive interaction facilitates a creation of polygonal filaments. The robustness of the shape transformation process with respect to external forces which are time and space periodic, is considered. It is shown that strong enough external driving makes the shape of the filament and the charge distribution along the filament highly irregular.

Research paper thumbnail of Nonlinear Science at the Dawn of the 21st Century

Lecture Notes in Physics, 2000

Page 1. Lecture Notes in Physics PLChristiansen MPSarensen AC Scott (Eds.) Nonlinear Science at t... more Page 1. Lecture Notes in Physics PLChristiansen MPSarensen AC Scott (Eds.) Nonlinear Science at the Dawn of the 21st Century (~ Springer Page 2. Lecture Notes in Physics Editorial Board R. Beig, Wien, Austria J. Ehlers, Potsdam ...

Research paper thumbnail of Analytical solutions of jam pattern formation on a ring for a class of optimal velocity traffic models

New Journal of Physics, 2009

Research paper thumbnail of Fluxons and their interactions in a system of three stacked Josephson junctions

Research paper thumbnail of Stability of fluxon motion in long Josephson junctions at high bias

Physical review. B, Condensed matter, 1988

Research paper thumbnail of Return-map for semiconductor lasers with optical feedback

1999 IEEE LEOS Annual Meeting Conference Proceedings. LEOS'99. 12th Annual Meeting. IEEE Lasers and Electro-Optics Society 1999 Annual Meeting (Cat. No.99CH37009), 1999

It is well known that a semiconductor laser exposed to moderate optical feedback and biased near ... more It is well known that a semiconductor laser exposed to moderate optical feedback and biased near threshold exhibits the phenomenon of low-frequency intensity fluctuations (LFF). While this behavior can be numerically simulated using the so-called Lang-Kobayshi model, the interpretation of the phenomenon has remained a controversy. The LFF consist of a sudden drop in intensity followed by a build-up in steps of the external cavity roundtrip time, τ, before a new drop-out occurs. The phenomenon has been attributed to a kind of chaotic itinerancy and a bifurcation cascade has been identified very recently. These results give insight into the behavior observed on a short time-scale, but do not explain some of the pronounced features of the LFF seen for moderate feedback levels; namely the stepwise build-up and its characteristic time of about 15 steps close to the solitary laser threshold. We present new results related to the slow time-scale behaviour of LFF which give a simple explanation of these general characteristics, as well as providing a new tool for studying the statistics of the LFF

Research paper thumbnail of Nonlinearity and disorder: Theory and applications. Proceedings of the 5th NATO advanced research workshop (ARW), Tashkent, Uzbekistan, October 2–6, 2001

... Ko'hna dastgoh aylanar hamon Bor olam g'ayb sirini ochib. Xaqiqat shu: hech... more ... Ko'hna dastgoh aylanar hamon Bor olam g'ayb sirini ochib. Xaqiqat shu: hech kim, hech qachon Qutilolmas taqdirdan qochib! Charx quyoshi kezadi jahon Gunoh, savob-ikki dunyodir. ... When God favours one man's soul He opens to him all ways. Mustakim R. Djumaev Page 22. ...

Research paper thumbnail of Fast 2D Simulation of Superconductors: a Multiscale Approach

Research paper thumbnail of Coherent dynamics of excitable and coupled β-cells

Research paper thumbnail of A Course on Applied Superconductivity Shared by Four Departments

Research paper thumbnail of NONLINEAR PROPERTIES OF THE BCS GAP EQUATION

Research paper thumbnail of Quasiperiodic Krönig-Penney Model on a Fibonacci Superlattice

Research paper thumbnail of Numerical Study of Bifurcations in the BCS Gap Equation

Research paper thumbnail of Nonlinear properteis of the BCS gap equation

Research paper thumbnail of Modeling and characterization of colliding pulse mode-locked (CPM) quantum well lasers

Proceedings of SPIE - The International Society for Optical Engineering

ABSTRACT

Research paper thumbnail of Nonlinearity in BCS Models of High-Tc Superconductors

Research paper thumbnail of ELECTROHYDRODYNAMIC STABILITY OF TWO-PHASE MICROFLOWS

Research paper thumbnail of Progress in industrial mathematics at ECMI ’96. Proceedings of the 9th conference of the European Consortium for Mathematics Industry, Lyngby, Denmark, June 1996

Research paper thumbnail of Escape angles in bulk chi((2)) soliton interactions

Research paper thumbnail of Experimental verification of soliton bunching in annular Josephson junction

Research paper thumbnail of Effects of charge-charge interactions and external fields in shape transformations of closed filaments

The role of charge-charge interactions in shape transformations of closed filaments induced by th... more The role of charge-charge interactions in shape transformations of closed filaments induced by the charge-curvature coupling is studied. It is shown that while sufficiently strong repulsive interaction between carriers makes a circular shape of the filament energetically more favorable with a spatially uniform charge distribution along the filament, the attractive interaction facilitates a creation of polygonal filaments. The robustness of the shape transformation process with respect to external forces which are time and space periodic, is considered. It is shown that strong enough external driving makes the shape of the filament and the charge distribution along the filament highly irregular.

Research paper thumbnail of Nonlinear Science at the Dawn of the 21st Century

Lecture Notes in Physics, 2000

Page 1. Lecture Notes in Physics PLChristiansen MPSarensen AC Scott (Eds.) Nonlinear Science at t... more Page 1. Lecture Notes in Physics PLChristiansen MPSarensen AC Scott (Eds.) Nonlinear Science at the Dawn of the 21st Century (~ Springer Page 2. Lecture Notes in Physics Editorial Board R. Beig, Wien, Austria J. Ehlers, Potsdam ...

Research paper thumbnail of Analytical solutions of jam pattern formation on a ring for a class of optimal velocity traffic models

New Journal of Physics, 2009

Research paper thumbnail of Fluxons and their interactions in a system of three stacked Josephson junctions

Research paper thumbnail of Stability of fluxon motion in long Josephson junctions at high bias

Physical review. B, Condensed matter, 1988

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