The Experts below are selected from a list of 58857 Experts worldwide ranked by ideXlab platform
Douglas A Stone - One of the best experts on this subject based on the ideXlab platform.
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controlling mode competition by tailoring the spatial pump distribution in a Laser a resonance based approach
Optics Express, 2016Co-Authors: Alexander Cerjan, Brandon Redding, Seng Fatt Liew, Hui Cao, Douglas A StoneAbstract:We introduce a simplified version of the steady-state ab initio Laser Theory for calculating the effects of mode competition in continuous wave Lasers using the passive cavity resonances. This new Theory harnesses widely available numerical methods that can efficiently calculate the passive cavity resonances, with negligible additional computational overhead. Using this Theory, we demonstrate that the pump profile of the Laser cavity can be optimized both for highly multi-mode and single-mode emission. An open source implementation of this method has been made available.
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quantitative test of general theories of the intrinsic Laser linewidth
Optics Express, 2015Co-Authors: Alexander Cerjan, Adi Pick, Yidong Chong, Steven G Johnson, Douglas A StoneAbstract:We perform a first-principles calculation of the quantum-limited Laser linewidth, testing the predictions of recently developed theories of the Laser linewidth based on fluctuations about the known steady-state Laser solutions against traditional forms of the Schawlow-Townes linewidth. The numerical study is based on finite-difference time-domain simulations of the semiclassical Maxwell-Bloch lasing equations, augmented with Langevin force terms, and includes the effects of dispersion, losses due to the open boundary of the Laser cavity, and non-linear coupling between the amplitude and phase fluctuations (α factor). We find quantitative agreement between the numerical results and the predictions of the noisy steady-state ab initio Laser Theory (N-SALT), both in the variation of the linewidth with output power, as well as the emergence of side-peaks due to relaxation oscillations.
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steady state ab initio Laser Theory for complex gain media
Optics Express, 2015Co-Authors: Alexander Cerjan, Yidong Chong, Douglas A StoneAbstract:We derive and test a generalization of the steady-state ab initio Laser Theory (SALT) to treat complex gain media. The generalized Theory (C-SALT) is able to treat atomic and molecular gain media with diffusion and multiple lasing transitions, and semiconductor gain media in the free carrier approximation including fully the effect of Pauli blocking. The key assumption of the Theory is stationarity of the level populations, which leads to coupled self-consistent equations for the populations and the lasing modes that fully include the effects of openness and non-linear spatial hole-burning. These equations can be solved efficiently for the steady-state lasing properties by a similar iteration procedure as in SALT, where a static gain medium with a single transition is assumed. The Theory is tested by comparison to much less efficient finite difference time domain (FDTD) methods and excellent agreement is found. Using C-SALT to analyze the effects of varying gain diffusion constant we demonstrate a cross-over between the regime of strong spatial hole burning with multimode lasing to a regime of negligible spatial hole burning, leading to gain-clamping, and single mode lasing. The effect of spatially inhomogeneous pumping combined with diffusion is also studied and a relevant length scale for spatial inhomogeneity to persist under these conditions is determined. For the semiconductor gain model, we demonstrate the frequency shift due to Pauli blocking as the pumping strength changes.
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steady state ab initio Laser Theory for complex gain media
arXiv: Optics, 2014Co-Authors: Alexander Cerjan, Yidong Chong, Douglas A StoneAbstract:We derive and test a generalization of Steady-State Ab Initio Laser Theory (SALT) to treat complex gain media. The generalized Theory (C-SALT) is able to treat atomic and molecular gain media with diffusion and multiple lasing transitions, and semiconductor gain media in the free carrier approximation including fully the effect of Pauli blocking. The key assumption of the Theory is stationarity of the level populations, which leads to coupled self-consistent equations for the populations and the lasing modes that fully include the effects of openness and non-linear spatial hole-burning. These equations can be solved efficiently for the steady-state lasing properties by a similar iteration procedure as in SALT, where a static gain medium with a single transition is assumed. The Theory is tested by comparison to much less efficient Finite Difference Time Domain (FDTD) methods and excellent agreement is found. Using C-SALT to analyze the effects of varying gain diffusion constant we demonstrate a cross-over between the regime of strong spatial hole burning with multimode lasing to a regime of negligible spatial hole burning, leading to gain-clamping, and single mode lasing. The effect of spatially inhomogeneous pumping combined with diffusion is also studied and a relevant length scale for spatial inhomogeneity to persist under these conditions is determined. For the semiconductor gain model, we demonstrate the frequency shift due to Pauli blocking as the pumping strength changes.
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steady state ab initio Laser Theory for n level Lasers
arXiv: Optics, 2011Co-Authors: Alexander Cerjan, Yidong Chong, Douglas A StoneAbstract:We show that Steady-state Ab initio Laser Theory (SALT) can be applied to find the stationary multimode lasing properties of an N-level Laser. This is achieved by mapping the N-level rate equations to an effective two-level model of the type solved by the SALT algorithm. This mapping yields excellent agreement with more computationally demanding N-level time domain solutions for the steady state.
Alexander Cerjan - One of the best experts on this subject based on the ideXlab platform.
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controlling mode competition by tailoring the spatial pump distribution in a Laser a resonance based approach
Optics Express, 2016Co-Authors: Alexander Cerjan, Brandon Redding, Seng Fatt Liew, Hui Cao, Douglas A StoneAbstract:We introduce a simplified version of the steady-state ab initio Laser Theory for calculating the effects of mode competition in continuous wave Lasers using the passive cavity resonances. This new Theory harnesses widely available numerical methods that can efficiently calculate the passive cavity resonances, with negligible additional computational overhead. Using this Theory, we demonstrate that the pump profile of the Laser cavity can be optimized both for highly multi-mode and single-mode emission. An open source implementation of this method has been made available.
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quantitative test of general theories of the intrinsic Laser linewidth
Optics Express, 2015Co-Authors: Alexander Cerjan, Adi Pick, Yidong Chong, Steven G Johnson, Douglas A StoneAbstract:We perform a first-principles calculation of the quantum-limited Laser linewidth, testing the predictions of recently developed theories of the Laser linewidth based on fluctuations about the known steady-state Laser solutions against traditional forms of the Schawlow-Townes linewidth. The numerical study is based on finite-difference time-domain simulations of the semiclassical Maxwell-Bloch lasing equations, augmented with Langevin force terms, and includes the effects of dispersion, losses due to the open boundary of the Laser cavity, and non-linear coupling between the amplitude and phase fluctuations (α factor). We find quantitative agreement between the numerical results and the predictions of the noisy steady-state ab initio Laser Theory (N-SALT), both in the variation of the linewidth with output power, as well as the emergence of side-peaks due to relaxation oscillations.
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steady state ab initio Laser Theory for complex gain media
Optics Express, 2015Co-Authors: Alexander Cerjan, Yidong Chong, Douglas A StoneAbstract:We derive and test a generalization of the steady-state ab initio Laser Theory (SALT) to treat complex gain media. The generalized Theory (C-SALT) is able to treat atomic and molecular gain media with diffusion and multiple lasing transitions, and semiconductor gain media in the free carrier approximation including fully the effect of Pauli blocking. The key assumption of the Theory is stationarity of the level populations, which leads to coupled self-consistent equations for the populations and the lasing modes that fully include the effects of openness and non-linear spatial hole-burning. These equations can be solved efficiently for the steady-state lasing properties by a similar iteration procedure as in SALT, where a static gain medium with a single transition is assumed. The Theory is tested by comparison to much less efficient finite difference time domain (FDTD) methods and excellent agreement is found. Using C-SALT to analyze the effects of varying gain diffusion constant we demonstrate a cross-over between the regime of strong spatial hole burning with multimode lasing to a regime of negligible spatial hole burning, leading to gain-clamping, and single mode lasing. The effect of spatially inhomogeneous pumping combined with diffusion is also studied and a relevant length scale for spatial inhomogeneity to persist under these conditions is determined. For the semiconductor gain model, we demonstrate the frequency shift due to Pauli blocking as the pumping strength changes.
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scalable numerical approach for the steady state ab initio Laser Theory
Physical Review A, 2014Co-Authors: S Esterhazy, Alexander Cerjan, Steven G Johnson, David V Liu, Matthias Liertzer, K G Makris, A D Stone, Jens Markus Melenk, Stefan RotterAbstract:We present an efficient and flexible method for solving the non-linear lasing equations of the steady-state ab initio Laser Theory. Our strategy is to solve the underlying system of partial differential equations directly, without the need of setting up a parametrized basis of constant flux states. We validate this approach in one-dimensional as well as in cylindrical systems, and demonstrate its scalability to full-vector three-dimensional calculations in photonic-crystal slabs. Our method paves the way for efficient and accurate simulations of microLasers which were previously inaccessible.
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steady state ab initio Laser Theory for complex gain media
arXiv: Optics, 2014Co-Authors: Alexander Cerjan, Yidong Chong, Douglas A StoneAbstract:We derive and test a generalization of Steady-State Ab Initio Laser Theory (SALT) to treat complex gain media. The generalized Theory (C-SALT) is able to treat atomic and molecular gain media with diffusion and multiple lasing transitions, and semiconductor gain media in the free carrier approximation including fully the effect of Pauli blocking. The key assumption of the Theory is stationarity of the level populations, which leads to coupled self-consistent equations for the populations and the lasing modes that fully include the effects of openness and non-linear spatial hole-burning. These equations can be solved efficiently for the steady-state lasing properties by a similar iteration procedure as in SALT, where a static gain medium with a single transition is assumed. The Theory is tested by comparison to much less efficient Finite Difference Time Domain (FDTD) methods and excellent agreement is found. Using C-SALT to analyze the effects of varying gain diffusion constant we demonstrate a cross-over between the regime of strong spatial hole burning with multimode lasing to a regime of negligible spatial hole burning, leading to gain-clamping, and single mode lasing. The effect of spatially inhomogeneous pumping combined with diffusion is also studied and a relevant length scale for spatial inhomogeneity to persist under these conditions is determined. For the semiconductor gain model, we demonstrate the frequency shift due to Pauli blocking as the pumping strength changes.
Yidong Chong - One of the best experts on this subject based on the ideXlab platform.
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topological insulator Laser Theory
Science, 2018Co-Authors: Gal Harari, Yidong Chong, Miguel A Bandres, Yaakov Lumer, Mikael C Rechtsman, Mercedeh Khajavikhan, Demetrios N Christodoulides, Mordechai SegevAbstract:INTRODUCTION Topological insulators emerged in condensed matter physics and constitute a new phase of matter, with insulating bulk and robust edge conductance that is immune to imperfections and disorder. To date, topological protection is known to be a ubiquitous phenomenon, occurring in many physical settings, ranging from photonics and cold atoms to acoustic, mechanical, and elastic systems. So far, however, most of these studies were carried out in entirely passive, linear, and conservative settings. RATIONALE We propose topological insulator Lasers: Lasers whose lasing mode exhibits topologically protected transport without magnetic fields. Extending topological physics to Lasers is far from natural. In fact, Lasers are built on foundations that are seemingly inconsistent with the essence of topological insulators: They require gain (and thus are non-Hermitian), they are nonlinear entities because the gain must be saturable, and they are open systems because they emit light. These properties, common to all Lasers, cast major doubts on the possibility of harnessing topological features to make a topological insulator Laser. Despite this common mindset, we show that the use of topological properties leads to highly efficient Lasers, robust to defects and disorder, with single-mode lasing even at conditions high above the Laser threshold. RESULTS We demonstrate that topological insulator Lasers are theoretically possible and experimentally feasible. We consider two configurations involving planar arrays of coupled active resonators. The first is based on the Haldane model, archetypical for topological systems. The second model, geared toward experiment, constitutes an aperiodic array architecture creating an artificial magnetic field. We show that by introducing saturable gain and loss, it is possible to make these systems lase in a topological edge state. In this way, the lasing mode exhibits topologically protected transport; the light propagates unidirectionally along the edges of the cavity, immune to scattering and disorder, unaffected by the shape of the edges. Moreover, we show that the underlying topological properties not only make the system robust to fabrication and operational disorder and defects, they also lead to a highly efficient single-mode lasing that remains single-mode even at gain values high above the Laser threshold. The figure describes the geometry and features of a topological insulator Laser based on the Haldane model while adding saturable gain, loss, and an output port. The cavity is a planar honeycomb lattice of coupled microring resonators, pumped at the perimeter with a lossy interior. We show that under these conditions, lasing occurs at the topological edge mode, which has unidirectional flux and is extended around the perimeter with almost-uniform intensity. The topological cavities exhibit higher efficiency than the trivial cavity, even under strong disorder. For the topological Laser with a small gap, the topological protection holds as long as the disorder level is smaller than the gap size. DISCUSSION The concept of the topological insulator Laser alters current understanding of the interplay between disorder and lasing, and opens exciting possibilities at the interface of topological physics and Laser science, such as topologically protected transport in systems with gain. We show here that the Laser system based on the archetypal Haldane model exhibits topologically protected transport, with features similar to those of its passive counterpart. This behavior means that this system is likely to have topological invariants, despite the nonhermiticity. Technologically, the topological insulator Laser offers an avenue to make many semiconductor Lasers operate as one single-mode high-power Laser. The topological insulator Laser constructed from an aperiodic array of resonators was realized experimentally in an all-dielectric platform, as described in the accompanying experimental paper by Bandres et al .
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quantitative test of general theories of the intrinsic Laser linewidth
Optics Express, 2015Co-Authors: Alexander Cerjan, Adi Pick, Yidong Chong, Steven G Johnson, Douglas A StoneAbstract:We perform a first-principles calculation of the quantum-limited Laser linewidth, testing the predictions of recently developed theories of the Laser linewidth based on fluctuations about the known steady-state Laser solutions against traditional forms of the Schawlow-Townes linewidth. The numerical study is based on finite-difference time-domain simulations of the semiclassical Maxwell-Bloch lasing equations, augmented with Langevin force terms, and includes the effects of dispersion, losses due to the open boundary of the Laser cavity, and non-linear coupling between the amplitude and phase fluctuations (α factor). We find quantitative agreement between the numerical results and the predictions of the noisy steady-state ab initio Laser Theory (N-SALT), both in the variation of the linewidth with output power, as well as the emergence of side-peaks due to relaxation oscillations.
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steady state ab initio Laser Theory for complex gain media
Optics Express, 2015Co-Authors: Alexander Cerjan, Yidong Chong, Douglas A StoneAbstract:We derive and test a generalization of the steady-state ab initio Laser Theory (SALT) to treat complex gain media. The generalized Theory (C-SALT) is able to treat atomic and molecular gain media with diffusion and multiple lasing transitions, and semiconductor gain media in the free carrier approximation including fully the effect of Pauli blocking. The key assumption of the Theory is stationarity of the level populations, which leads to coupled self-consistent equations for the populations and the lasing modes that fully include the effects of openness and non-linear spatial hole-burning. These equations can be solved efficiently for the steady-state lasing properties by a similar iteration procedure as in SALT, where a static gain medium with a single transition is assumed. The Theory is tested by comparison to much less efficient finite difference time domain (FDTD) methods and excellent agreement is found. Using C-SALT to analyze the effects of varying gain diffusion constant we demonstrate a cross-over between the regime of strong spatial hole burning with multimode lasing to a regime of negligible spatial hole burning, leading to gain-clamping, and single mode lasing. The effect of spatially inhomogeneous pumping combined with diffusion is also studied and a relevant length scale for spatial inhomogeneity to persist under these conditions is determined. For the semiconductor gain model, we demonstrate the frequency shift due to Pauli blocking as the pumping strength changes.
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steady state ab initio Laser Theory for complex gain media
arXiv: Optics, 2014Co-Authors: Alexander Cerjan, Yidong Chong, Douglas A StoneAbstract:We derive and test a generalization of Steady-State Ab Initio Laser Theory (SALT) to treat complex gain media. The generalized Theory (C-SALT) is able to treat atomic and molecular gain media with diffusion and multiple lasing transitions, and semiconductor gain media in the free carrier approximation including fully the effect of Pauli blocking. The key assumption of the Theory is stationarity of the level populations, which leads to coupled self-consistent equations for the populations and the lasing modes that fully include the effects of openness and non-linear spatial hole-burning. These equations can be solved efficiently for the steady-state lasing properties by a similar iteration procedure as in SALT, where a static gain medium with a single transition is assumed. The Theory is tested by comparison to much less efficient Finite Difference Time Domain (FDTD) methods and excellent agreement is found. Using C-SALT to analyze the effects of varying gain diffusion constant we demonstrate a cross-over between the regime of strong spatial hole burning with multimode lasing to a regime of negligible spatial hole burning, leading to gain-clamping, and single mode lasing. The effect of spatially inhomogeneous pumping combined with diffusion is also studied and a relevant length scale for spatial inhomogeneity to persist under these conditions is determined. For the semiconductor gain model, we demonstrate the frequency shift due to Pauli blocking as the pumping strength changes.
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steady state ab initio Laser Theory for n level Lasers
arXiv: Optics, 2011Co-Authors: Alexander Cerjan, Yidong Chong, Douglas A StoneAbstract:We show that Steady-state Ab initio Laser Theory (SALT) can be applied to find the stationary multimode lasing properties of an N-level Laser. This is achieved by mapping the N-level rate equations to an effective two-level model of the type solved by the SALT algorithm. This mapping yields excellent agreement with more computationally demanding N-level time domain solutions for the steady state.
Murray Sargent - One of the best experts on this subject based on the ideXlab platform.
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multimode description of self mode locking in a single section quantum dot Laser
Optics Express, 2020Co-Authors: Weng W Chow, Songtao Liu, Zeyu Zhang, John E Bowers, Murray SargentAbstract:This paper describes a Theory for mode locking and frequency comb generation by four-wave mixing in a semiconductor quantum-dot active medium. The derivation uses a multimode semiclassical Laser Theory that accounts for fast carrier collisions within an inhomogeneous distribution of quantum dots. Numerical simulations are presented to illustrate the role of active medium nonlinearities in mode competition, gain saturation, carrier-induced refractive index and creation of combination tones that lead to locking of beat frequencies among lasing modes in the presence of cavity material dispersion.
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semiconductor Laser physics
1994Co-Authors: Weng W Chow, Stephan W Koch, Murray SargentAbstract:1. Semiconductor Laser Diodes 2. Basic Concepts 3. Free-Carrier Theory 4. Coulomb Effects 5. Many-Body Gain 6. Band Mixing and Strain in Quantum Wells 7. Semiclassical Laser Theory 8. Multimode Operation 9. Quantum Theory of the Laser 10. Propagation Effects 11. Beyond Quasiequilibrium Theory, Appendices A-e, Index
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Theory of a multimode quasiequilibrium semiconductor Laser
Physical Review A, 1993Co-Authors: Murray SargentAbstract:This paper gives a simple plane-wave multimode semiconductor-Laser Theory valid near threshold under the quasiequilibrium assumption that the total field envelope varies little in the intraband scattering times. Subject to these limitations, the Theory is able to describe the full many-body effects in the semiconductor medium for a variety of field configurations including unidirectional, bidirectional, and two-mirror standing-wave Lasers with nonuniform gain distributions. The Theory predicts that spatial-hole burning can lead to multimode operation and that bidirectional ring-Laser operation cannot occur. Generalization to larger field intensities is discussed within the framenuork of the quasiequilibrium assumption
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elements of quantum optics
1991Co-Authors: Pierre Meystre, Murray SargentAbstract:Classical Electromagnetic Fields.- Classical Nonlinear Optics.- Quantum Mechanical Background.- Mixtures and the Density Operator.- CW Field Interactions.- Mechanical Effects of Light.- to Laser Theory.- Optical Bistability.- Saturation Spectroscopy.- Three and Four Wave Mixing.- Time-Varying Phenomena in Cavities.- Coherent Transients.- Field Quantization.- Interaction Between Atoms and Quantized Fields.- System-Reservoir Interactions.- Resonance Fluorescence.- Squeezed States of Light.- Cavity Quantum Electrodynamics.- Quantum Theory of a Laser.- Entanglement, Bell Inequalities and Quantum Information.
Peter Michler - One of the best experts on this subject based on the ideXlab platform.
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influence of the spontaneous optical emission factor β on the first order coherence of a semiconductor microcavity Laser
Physical Review B, 2008Co-Authors: Serkan Ates, S M Ulrich, C Gies, Jan Wiersig, Alex Loffler, Frank Jahnke, Alfred Forchel, Stephan Reitzenstein, Peter MichlerAbstract:A systematic experimental and theoretical study of first-order coherence properties of high-$\ensuremath{\beta}$ quantum-dot micropillar Lasers is presented. A nonlinear increase in the coherence length is found in the transition regime from spontaneous to dominantly stimulated emission. This increase is accompanied by a qualitative change in the first-order field-correlation function ${g}^{(1)}(\ensuremath{\tau})$ from a Gaussian-type profile to an exponential behavior, which is in excellent agreement with a microscopic semiconductor Laser Theory. Our results also demonstrate a decreasing coherence length with increasing spontaneous emission coupling $\ensuremath{\beta}$, thus raising questions about the practicability of high-$\ensuremath{\beta}$ Lasers for device applications.
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photon statistics of semiconductor microcavity Lasers
Physical Review Letters, 2007Co-Authors: S M Ulrich, C Gies, Serkan Ates, Jan Wiersig, Alex Loffler, C Hofmann, Frank Jahnke, Alfred Forchel, Stephan Reitzenstein, Peter MichlerAbstract:: We present measurements of first- and second-order coherence of quantum-dot micropillar Lasers together with a semiconductor Laser Theory. Our results show a broad threshold region for the observed high-beta microcavities. The intensity jump is accompanied by both pronounced photon intensity fluctuations and strong coherence length changes. The investigations clearly visualize a smooth transition from spontaneous to predominantly stimulated emission which becomes harder to determine for high beta. In our Theory, a microscopic approach is used to incorporate the semiconductor nature of quantum dots. The results are in agreement with the experimental intensity traces and the photon statistics measurements.
