Xavier Hachair - Academia.edu (original) (raw)
Papers by Xavier Hachair
IEEE Journal of Selected Topics in Quantum Electronics, 2006
We experimentally demonstrate the existence and the control of cavity solitons in externally driv... more We experimentally demonstrate the existence and the control of cavity solitons in externally driven vertical-cavity semiconductor lasers above threshold. A model including material polarization dynamics is used to predict and confirm the experimental findings.
IEEE Journal of Quantum Electronics, 2004
In this paper, we experimentally analyze the modal dynamics of quantum-well semiconductor lasers.... more In this paper, we experimentally analyze the modal dynamics of quantum-well semiconductor lasers. Modal switching is the dominant feature for semiconductor lasers that exhibit two or several active longitudinal modes in their time-averaged optical spectrum. In quantum-well lasers, these dynamics involve a periodic switching among several longitudinal modes, which follows a well-determined sequence from the bluest to the reddest mode in the optical spectrum. This feature is radically different from the well-known noise-driven mode-hopping occurring in bulk lasers which involves only two main modes. We analyze the differences in modal dynamics for these two kinds of laser by comparing the modal switching statistics and by studying the effects of noise and modulation in the pumping current.
IEEE Journal of Quantum Electronics, 2005
We analyze theoretically and experimentally how the modal dynamics of quantum-well semiconductor ... more We analyze theoretically and experimentally how the modal dynamics of quantum-well semiconductor lasers is affected by weak optical feedback. Without feedback, these lasers exhibit a regular switching among several longitudinal modes, following a well determined modal sequence and leaving the total intensity output constant. Using a multimode theoretical model we have identified the four wave mixing as the dominant mechanism at the origin of these intriguing dynamics, while the asymmetry of the susceptibility function of semiconductor materials allows to explain the modal sequence. In this manuscript we show that these dynamics, which is almost insensitive to current noise or modulation, is instead extremely sensitive to optical feedback. The experimental results are satisfactorily compared with the numerical predictions of the model, properly adapted for including weak optical feedback.
L’etude experimentale des structures spatiales localisees independantes et controlables nommees «... more L’etude experimentale des structures spatiales localisees independantes et controlables nommees « solitons de cavite » dans une cavite semi-conductrice, constitue le cadre du travail presente dans ce memoire. Cette etude qui repose sur une experience d’injection optique dans le plan transverse d’un laser semi-conducteur a cavite verticale (VCSEL), nous a permis de definir les regions de parametres ou ces structures existent, ainsi que les differentes caracteristiques de leur allumage aussi bien spontane que controle. La possibilite de definir leurs positions ainsi que celle de les mouvoir en utilisant un faisceau d’injection compose de franges d’interferences ou possedant un gradient de phase, a aussi ete demontree. Dans le but de pouvoir controler le transitoire de ces structures, une etude sur celui des lasers de classe B a ete realisee. La suppression du pic de surintensite, des oscillations de relaxations et la reduction du temps de retard present lors de ce transitoire ont ete ...
2007 European Conference on Lasers and Electro-Optics and the International Quantum Electronics Conference, 2007
ABSTRACT The transverse emission characteristics of an optically pumped vertical external cavity ... more ABSTRACT The transverse emission characteristics of an optically pumped vertical external cavity surface emitting laser (VECSEL) operating in a high Fresnel number regime was investigated. This property is sought for the realization of a cavity soliton laser (CSL). Low to very high order flower-like transverse modes were observed experimentally. Output intensity of the VECSEL for different positions of the intracavity lens corresponding to an increasing Fresnel number were shown.
2007 European Conference on Lasers and Electro-Optics and the International Quantum Electronics Conference, 2007
ABSTRACT Cavity solitons (CSs) are self-localized spots formed in the transverse plane of a nonli... more ABSTRACT Cavity solitons (CSs) are self-localized spots formed in the transverse plane of a nonlinear cavity. They have been observed in various macroscopic systems, and predicted and observed in microscopic, semiconductor-based systems too. They are formed in a spatially extended, bistable, and modulationally unstable system driven by a coherent field (holding beam) and appear generally as bright spots sitting on a dark background.
Semiconductor Lasers and Laser Dynamics, 2004
In this manuscript we analyze the modal dynamics of multimode semiconductor quantum-well lasers. ... more In this manuscript we analyze the modal dynamics of multimode semiconductor quantum-well lasers. Modal switching is the dominant feature of the devices analyzed and it obeys a highly organized antiphase dynamics which leads to an almost constant total intensity output. For each active mode a regular switching at frequencies of few MHz is observed. The activation order of the modes follows a well defined sequence starting from the lowest wavelength (bluest) mode to the highest wavelength (reddest) mode, then the sequence starts again from the bluest mode. Using a multimode theoretical model and a simpler phenomenological model we identify that four wave mixing is the dominant mechanism at the origin of the observed dynamics. The asymmetry of the susceptibility function of semiconductor materials allows to explain the optical frequency sequence.
Conference on Lasers and Electro-Optics/International Quantum Electronics Conference, 2009
ABSTRACT We present experimental results on the formation and control of single and cluster state... more ABSTRACT We present experimental results on the formation and control of single and cluster states of cavity solitons in a vertical cavity semiconductor optical amplifier. A parameter region where cluster states are inhibited is demonstrated.
SPIE Proceedings, 2004
ABSTRACT In this manuscript we analyze experimentally the noise effects on the modal dynamics of ... more ABSTRACT In this manuscript we analyze experimentally the noise effects on the modal dynamics of semiconductor lasers. Modal switching is the dominant feature of multimode semiconductor lasers. In bulk lasers, two modes coexisting for the same values of the parameters switch under the action of the noise present into the system (mode-hopping). In this kind of laser we give evidence of stochastic resonance of the mode-hopping under modulation of the laser pump. In quantum-well lasers the modal dynamics is radically different: it consists of a periodic switching among several longitudinal modes, following a well determined sequence from the bluest to the reddest mode in the optical spectrum. The switching dynamics of the modes obeys to a perfect antiphase leading to an almost constant total intensity output.
CLEO/Europe - EQEC 2009 - European Conference on Lasers and Electro-Optics and the European Quantum Electronics Conference, 2009
ABSTRACT We observe experimentally and confirm numerically spatially localized light structures w... more ABSTRACT We observe experimentally and confirm numerically spatially localized light structures with linear polarization, orthogonal to the principal polarization in a 40 mum diameter vertical-cavity surface emitting laser biased above the lasing threshold.
2009 11th International Conference on Transparent Optical Networks, 2009
ABSTRACT Due to current crowding, the laser emission in medium size VCSELs starts at threshold in... more ABSTRACT Due to current crowding, the laser emission in medium size VCSELs starts at threshold in a linearly polarized ldquoflower moderdquo concentrated at the laser aperture periphery. Introducing a holding beam with orthogonal liner polarization we observe localized structure in the center of the device in the orthogonal polarization while the VCSEL keeps lasing in the same flower-mode. We support theoretically our experimental findings using two different VCSEL models, which account for both polarization and spatial dynamics.
Semiconductor Lasers and Laser Dynamics, 2004
ABSTRACT Cavity solitons are stationary self-organized bright intensity peaks which form over a h... more ABSTRACT Cavity solitons are stationary self-organized bright intensity peaks which form over a homogeneous background in the section of broad area radiation beams. They are generated by shining a writing/erasing laser pulse into a nonlinear optical cavity, driven by a holding beam. The ability to control their location and their motion by introducing phase or amplitude gradients in the holding beam makes them interesting as mobile pixels for all-optical processing units. We show the generation of a number of cavity solitons in broad area vertical cavity semiconductor microresonators electrically pumped above transparency but slightly below threshold. The observed spots can be written, erased and manipulated as independent objects. We analyze experimentally the cavity solitons domain of existence in the parameter space and how their characteristics are affected by inhomogeneities and impurities of the vertical cavity devices. A theoretical model, keeping into account the devices characteristics, reproduces numerically the experimental observations with good agreement.
Proceedings of SPIE - The International Society for Optical Engineering, 2002
ABSTRACT Direct modulation of the injected current still represents an attractive and inexpensive... more ABSTRACT Direct modulation of the injected current still represents an attractive and inexpensive technique for encoding information in the output of a semiconductor laser. The growing requirements in volume of information to be transmitted and their conflict with the progressive, and rapid, degradation of the signal at high speeds have made this simple technical solution less and less attractive. A brief analysis of the sources of the problem is offered. A viable and inexpensive way of improving DM's performance is discussed. High quality signals are predicted at data transmission speeds that exceed by over an order of magnitude those obtainable with DM.
Conference on Lasers and Electro-Optics/International Quantum Electronics Conference and Photonic Applications Systems Technologies, 2004
We show the generation of several cavity solitons in driven broad-area vertical-cavity semiconduc... more We show the generation of several cavity solitons in driven broad-area vertical-cavity semiconductor lasers below threshold. The switching process is analysed in details, and a theoretical interpretation is provided to confirm and steer experimental findings
EQEC '05. European Quantum Electronics Conference, 2005., 2005
This work experimentally and numerically investigates the cavity solitons switch-on process in se... more This work experimentally and numerically investigates the cavity solitons switch-on process in semiconductor microresonators. This is a highly relevant feature to applications since its duration determines the maximum speed at which the device can be addressed. Numerical simulations show a very good agreement with the experimental findings, both from the qualitative and quantitative viewpoints.
CLEO/Europe. 2005 Conference on Lasers and Electro-Optics Europe, 2005., 2005
ABSTRACT In the present work we provide a complete and deep description of the characteristics of... more ABSTRACT In the present work we provide a complete and deep description of the characteristics of the cavity solitons in semiconductor cavities. We demonstrate the generation of quite a number of CSs in the transverse section, and perform a careful analysis of the switching process of CSs. The laser where we are intended to generate the cavity solitons is an oxidized bottom-emitter VCSEL emitting around 970 nm at threshold.
CLEO:2011 - Laser Applications to Photonic Applications, 2011
ABSTRACT We have demonstrated coherent emission at 1.55μm from nanoscale lasers at room temperatu... more ABSTRACT We have demonstrated coherent emission at 1.55μm from nanoscale lasers at room temperature under gain-switched operation and studied their characteristics particularly with regard to the pulsed excitation rate, a feature that is important for high bit-rate data transmission.
Conference on Lasers and Electro-Optics 2010, 2010
Abstract We will present a further understanding of the threshold transition in lasers operating ... more Abstract We will present a further understanding of the threshold transition in lasers operating at nanoscale, by measuring the threshold transition from a quantum, statistical and dynamical points of view at room temperature and telecommunication wavelengths.
Nonlinear Guided Waves and Their Applications, 2005
We experimentally demonstrate the existence and the control of cavity solitons in externally driv... more We experimentally demonstrate the existence and the control of cavity solitons in externally driven vertical-cavity semiconductor lasers above threshold. A model including material polarization dynamics is used to predict and confirm the experimental findings.
Physical Review Letters, 2008
We report on experimental observations of homoclinic snaking in a vertical-cavity semiconductor o... more We report on experimental observations of homoclinic snaking in a vertical-cavity semiconductor optical amplifier. Our observations in a quasi-one-dimensional and two-dimensional configurations agree qualitatively well with what is expected from recent theoretical and numerical studies. In particular, we show the bifurcation sequence leading to a snaking bifurcation diagram linking single localized states to ''localized patterns'' or clusters of localized states and demonstrate a parameter region where cluster states are inhibited.
IEEE Journal of Selected Topics in Quantum Electronics, 2006
We experimentally demonstrate the existence and the control of cavity solitons in externally driv... more We experimentally demonstrate the existence and the control of cavity solitons in externally driven vertical-cavity semiconductor lasers above threshold. A model including material polarization dynamics is used to predict and confirm the experimental findings.
IEEE Journal of Quantum Electronics, 2004
In this paper, we experimentally analyze the modal dynamics of quantum-well semiconductor lasers.... more In this paper, we experimentally analyze the modal dynamics of quantum-well semiconductor lasers. Modal switching is the dominant feature for semiconductor lasers that exhibit two or several active longitudinal modes in their time-averaged optical spectrum. In quantum-well lasers, these dynamics involve a periodic switching among several longitudinal modes, which follows a well-determined sequence from the bluest to the reddest mode in the optical spectrum. This feature is radically different from the well-known noise-driven mode-hopping occurring in bulk lasers which involves only two main modes. We analyze the differences in modal dynamics for these two kinds of laser by comparing the modal switching statistics and by studying the effects of noise and modulation in the pumping current.
IEEE Journal of Quantum Electronics, 2005
We analyze theoretically and experimentally how the modal dynamics of quantum-well semiconductor ... more We analyze theoretically and experimentally how the modal dynamics of quantum-well semiconductor lasers is affected by weak optical feedback. Without feedback, these lasers exhibit a regular switching among several longitudinal modes, following a well determined modal sequence and leaving the total intensity output constant. Using a multimode theoretical model we have identified the four wave mixing as the dominant mechanism at the origin of these intriguing dynamics, while the asymmetry of the susceptibility function of semiconductor materials allows to explain the modal sequence. In this manuscript we show that these dynamics, which is almost insensitive to current noise or modulation, is instead extremely sensitive to optical feedback. The experimental results are satisfactorily compared with the numerical predictions of the model, properly adapted for including weak optical feedback.
L’etude experimentale des structures spatiales localisees independantes et controlables nommees «... more L’etude experimentale des structures spatiales localisees independantes et controlables nommees « solitons de cavite » dans une cavite semi-conductrice, constitue le cadre du travail presente dans ce memoire. Cette etude qui repose sur une experience d’injection optique dans le plan transverse d’un laser semi-conducteur a cavite verticale (VCSEL), nous a permis de definir les regions de parametres ou ces structures existent, ainsi que les differentes caracteristiques de leur allumage aussi bien spontane que controle. La possibilite de definir leurs positions ainsi que celle de les mouvoir en utilisant un faisceau d’injection compose de franges d’interferences ou possedant un gradient de phase, a aussi ete demontree. Dans le but de pouvoir controler le transitoire de ces structures, une etude sur celui des lasers de classe B a ete realisee. La suppression du pic de surintensite, des oscillations de relaxations et la reduction du temps de retard present lors de ce transitoire ont ete ...
2007 European Conference on Lasers and Electro-Optics and the International Quantum Electronics Conference, 2007
ABSTRACT The transverse emission characteristics of an optically pumped vertical external cavity ... more ABSTRACT The transverse emission characteristics of an optically pumped vertical external cavity surface emitting laser (VECSEL) operating in a high Fresnel number regime was investigated. This property is sought for the realization of a cavity soliton laser (CSL). Low to very high order flower-like transverse modes were observed experimentally. Output intensity of the VECSEL for different positions of the intracavity lens corresponding to an increasing Fresnel number were shown.
2007 European Conference on Lasers and Electro-Optics and the International Quantum Electronics Conference, 2007
ABSTRACT Cavity solitons (CSs) are self-localized spots formed in the transverse plane of a nonli... more ABSTRACT Cavity solitons (CSs) are self-localized spots formed in the transverse plane of a nonlinear cavity. They have been observed in various macroscopic systems, and predicted and observed in microscopic, semiconductor-based systems too. They are formed in a spatially extended, bistable, and modulationally unstable system driven by a coherent field (holding beam) and appear generally as bright spots sitting on a dark background.
Semiconductor Lasers and Laser Dynamics, 2004
In this manuscript we analyze the modal dynamics of multimode semiconductor quantum-well lasers. ... more In this manuscript we analyze the modal dynamics of multimode semiconductor quantum-well lasers. Modal switching is the dominant feature of the devices analyzed and it obeys a highly organized antiphase dynamics which leads to an almost constant total intensity output. For each active mode a regular switching at frequencies of few MHz is observed. The activation order of the modes follows a well defined sequence starting from the lowest wavelength (bluest) mode to the highest wavelength (reddest) mode, then the sequence starts again from the bluest mode. Using a multimode theoretical model and a simpler phenomenological model we identify that four wave mixing is the dominant mechanism at the origin of the observed dynamics. The asymmetry of the susceptibility function of semiconductor materials allows to explain the optical frequency sequence.
Conference on Lasers and Electro-Optics/International Quantum Electronics Conference, 2009
ABSTRACT We present experimental results on the formation and control of single and cluster state... more ABSTRACT We present experimental results on the formation and control of single and cluster states of cavity solitons in a vertical cavity semiconductor optical amplifier. A parameter region where cluster states are inhibited is demonstrated.
SPIE Proceedings, 2004
ABSTRACT In this manuscript we analyze experimentally the noise effects on the modal dynamics of ... more ABSTRACT In this manuscript we analyze experimentally the noise effects on the modal dynamics of semiconductor lasers. Modal switching is the dominant feature of multimode semiconductor lasers. In bulk lasers, two modes coexisting for the same values of the parameters switch under the action of the noise present into the system (mode-hopping). In this kind of laser we give evidence of stochastic resonance of the mode-hopping under modulation of the laser pump. In quantum-well lasers the modal dynamics is radically different: it consists of a periodic switching among several longitudinal modes, following a well determined sequence from the bluest to the reddest mode in the optical spectrum. The switching dynamics of the modes obeys to a perfect antiphase leading to an almost constant total intensity output.
CLEO/Europe - EQEC 2009 - European Conference on Lasers and Electro-Optics and the European Quantum Electronics Conference, 2009
ABSTRACT We observe experimentally and confirm numerically spatially localized light structures w... more ABSTRACT We observe experimentally and confirm numerically spatially localized light structures with linear polarization, orthogonal to the principal polarization in a 40 mum diameter vertical-cavity surface emitting laser biased above the lasing threshold.
2009 11th International Conference on Transparent Optical Networks, 2009
ABSTRACT Due to current crowding, the laser emission in medium size VCSELs starts at threshold in... more ABSTRACT Due to current crowding, the laser emission in medium size VCSELs starts at threshold in a linearly polarized ldquoflower moderdquo concentrated at the laser aperture periphery. Introducing a holding beam with orthogonal liner polarization we observe localized structure in the center of the device in the orthogonal polarization while the VCSEL keeps lasing in the same flower-mode. We support theoretically our experimental findings using two different VCSEL models, which account for both polarization and spatial dynamics.
Semiconductor Lasers and Laser Dynamics, 2004
ABSTRACT Cavity solitons are stationary self-organized bright intensity peaks which form over a h... more ABSTRACT Cavity solitons are stationary self-organized bright intensity peaks which form over a homogeneous background in the section of broad area radiation beams. They are generated by shining a writing/erasing laser pulse into a nonlinear optical cavity, driven by a holding beam. The ability to control their location and their motion by introducing phase or amplitude gradients in the holding beam makes them interesting as mobile pixels for all-optical processing units. We show the generation of a number of cavity solitons in broad area vertical cavity semiconductor microresonators electrically pumped above transparency but slightly below threshold. The observed spots can be written, erased and manipulated as independent objects. We analyze experimentally the cavity solitons domain of existence in the parameter space and how their characteristics are affected by inhomogeneities and impurities of the vertical cavity devices. A theoretical model, keeping into account the devices characteristics, reproduces numerically the experimental observations with good agreement.
Proceedings of SPIE - The International Society for Optical Engineering, 2002
ABSTRACT Direct modulation of the injected current still represents an attractive and inexpensive... more ABSTRACT Direct modulation of the injected current still represents an attractive and inexpensive technique for encoding information in the output of a semiconductor laser. The growing requirements in volume of information to be transmitted and their conflict with the progressive, and rapid, degradation of the signal at high speeds have made this simple technical solution less and less attractive. A brief analysis of the sources of the problem is offered. A viable and inexpensive way of improving DM's performance is discussed. High quality signals are predicted at data transmission speeds that exceed by over an order of magnitude those obtainable with DM.
Conference on Lasers and Electro-Optics/International Quantum Electronics Conference and Photonic Applications Systems Technologies, 2004
We show the generation of several cavity solitons in driven broad-area vertical-cavity semiconduc... more We show the generation of several cavity solitons in driven broad-area vertical-cavity semiconductor lasers below threshold. The switching process is analysed in details, and a theoretical interpretation is provided to confirm and steer experimental findings
EQEC '05. European Quantum Electronics Conference, 2005., 2005
This work experimentally and numerically investigates the cavity solitons switch-on process in se... more This work experimentally and numerically investigates the cavity solitons switch-on process in semiconductor microresonators. This is a highly relevant feature to applications since its duration determines the maximum speed at which the device can be addressed. Numerical simulations show a very good agreement with the experimental findings, both from the qualitative and quantitative viewpoints.
CLEO/Europe. 2005 Conference on Lasers and Electro-Optics Europe, 2005., 2005
ABSTRACT In the present work we provide a complete and deep description of the characteristics of... more ABSTRACT In the present work we provide a complete and deep description of the characteristics of the cavity solitons in semiconductor cavities. We demonstrate the generation of quite a number of CSs in the transverse section, and perform a careful analysis of the switching process of CSs. The laser where we are intended to generate the cavity solitons is an oxidized bottom-emitter VCSEL emitting around 970 nm at threshold.
CLEO:2011 - Laser Applications to Photonic Applications, 2011
ABSTRACT We have demonstrated coherent emission at 1.55μm from nanoscale lasers at room temperatu... more ABSTRACT We have demonstrated coherent emission at 1.55μm from nanoscale lasers at room temperature under gain-switched operation and studied their characteristics particularly with regard to the pulsed excitation rate, a feature that is important for high bit-rate data transmission.
Conference on Lasers and Electro-Optics 2010, 2010
Abstract We will present a further understanding of the threshold transition in lasers operating ... more Abstract We will present a further understanding of the threshold transition in lasers operating at nanoscale, by measuring the threshold transition from a quantum, statistical and dynamical points of view at room temperature and telecommunication wavelengths.
Nonlinear Guided Waves and Their Applications, 2005
We experimentally demonstrate the existence and the control of cavity solitons in externally driv... more We experimentally demonstrate the existence and the control of cavity solitons in externally driven vertical-cavity semiconductor lasers above threshold. A model including material polarization dynamics is used to predict and confirm the experimental findings.
Physical Review Letters, 2008
We report on experimental observations of homoclinic snaking in a vertical-cavity semiconductor o... more We report on experimental observations of homoclinic snaking in a vertical-cavity semiconductor optical amplifier. Our observations in a quasi-one-dimensional and two-dimensional configurations agree qualitatively well with what is expected from recent theoretical and numerical studies. In particular, we show the bifurcation sequence leading to a snaking bifurcation diagram linking single localized states to ''localized patterns'' or clusters of localized states and demonstrate a parameter region where cluster states are inhibited.