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Martin Weitz - One of the best experts on this subject based on the ideXlab platform.
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bose einstein condensation of photons in an optical microcavity
Nature, 2010Co-Authors: Jan Klaers, Julian Schmitt, Frank Vewinger, Martin WeitzAbstract:Bose–Einstein condensation has been observed in several physical systems, but is not predicted to occur for blackbody radiation such as photons. However, it becomes theoretically possible in the presence of thermalization processes that conserve photon number. Martin Weitz and colleagues have now realized such conditions experimentally, observing Bose–Einstein condensation of photons in a dye-filled optical microcavity. The effect is of interest for fundamental studies and may lead to new coherent ultraviolet sources. Bose–Einstein condensation has been observed in several physical systems, but is not predicted to occur for blackbody radiation such as photons. However, it becomes theoretically possible in the presence of thermalization processes that conserve photon number. These authors experimentally realise such conditions, observing Bose–Einstein condensation of photons in a dye-filled optical microcavity. The effect is of interest for fundamental studies and may lead to new coherent ultraviolet sources. Bose–Einstein condensation (BEC)—the macroscopic ground-State accumulation of particles with integer spin (bosons) at low temperature and high density—has been observed in several physical systems1,2,3,4,5,6,7,8,9, including cold atomic gases and solid-State quasiparticles. However, the most omnipresent Bose gas, blackbody radiation (radiation in thermal equilibrium with the cavity walls) does not show this phase transition. In such systems photons have a vanishing chemical potential, meaning that their number is not conserved when the temperature of the photon gas is varied10; at low temperatures, photons disappear in the cavity walls instead of occupying the cavity ground State. Theoretical works have considered thermalization processes that conserve photon number (a prerequisite for BEC), involving Compton scattering with a gas of thermal electrons11 or photon–photon scattering in a nonlinear resonator configuration12,13. Number-conserving thermalization was experimentally observed14 for a two-dimensional photon gas in a dye-filled optical microcavity, which acts as a ‘white-wall’ box. Here we report the observation of a Bose–Einstein condensate of photons in this system. The cavity mirrors provide both a confining potential and a non-vanishing effective photon mass, making the system formally equivalent to a two-dimensional gas of trapped, massive bosons. The photons thermalize to the temperature of the dye solution (room temperature) by multiple scattering with the dye molecules. Upon increasing the photon density, we observe the following BEC signatures: the photon energies have a Bose–Einstein distribution with a massively populated ground-State Mode on top of a broad thermal wing; the phase transition occurs at the expected photon density and exhibits the predicted dependence on cavity geometry; and the ground-State Mode emerges even for a spatially displaced pump spot. The prospects of the observed effects include studies of extremely weakly interacting low-dimensional Bose gases9 and new coherent ultraviolet sources15.
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bose einstein condensation of photons in an optical microcavity
Nature, 2010Co-Authors: Jan Klaers, Julian Schmitt, Frank Vewinger, Martin WeitzAbstract:Bose–Einstein condensation has been observed in several physical systems, but is not predicted to occur for blackbody radiation such as photons. However, it becomes theoretically possible in the presence of thermalization processes that conserve photon number. Martin Weitz and colleagues have now realized such conditions experimentally, observing Bose–Einstein condensation of photons in a dye-filled optical microcavity. The effect is of interest for fundamental studies and may lead to new coherent ultraviolet sources. Bose–Einstein condensation has been observed in several physical systems, but is not predicted to occur for blackbody radiation such as photons. However, it becomes theoretically possible in the presence of thermalization processes that conserve photon number. These authors experimentally realise such conditions, observing Bose–Einstein condensation of photons in a dye-filled optical microcavity. The effect is of interest for fundamental studies and may lead to new coherent ultraviolet sources. Bose–Einstein condensation (BEC)—the macroscopic ground-State accumulation of particles with integer spin (bosons) at low temperature and high density—has been observed in several physical systems1,2,3,4,5,6,7,8,9, including cold atomic gases and solid-State quasiparticles. However, the most omnipresent Bose gas, blackbody radiation (radiation in thermal equilibrium with the cavity walls) does not show this phase transition. In such systems photons have a vanishing chemical potential, meaning that their number is not conserved when the temperature of the photon gas is varied10; at low temperatures, photons disappear in the cavity walls instead of occupying the cavity ground State. Theoretical works have considered thermalization processes that conserve photon number (a prerequisite for BEC), involving Compton scattering with a gas of thermal electrons11 or photon–photon scattering in a nonlinear resonator configuration12,13. Number-conserving thermalization was experimentally observed14 for a two-dimensional photon gas in a dye-filled optical microcavity, which acts as a ‘white-wall’ box. Here we report the observation of a Bose–Einstein condensate of photons in this system. The cavity mirrors provide both a confining potential and a non-vanishing effective photon mass, making the system formally equivalent to a two-dimensional gas of trapped, massive bosons. The photons thermalize to the temperature of the dye solution (room temperature) by multiple scattering with the dye molecules. Upon increasing the photon density, we observe the following BEC signatures: the photon energies have a Bose–Einstein distribution with a massively populated ground-State Mode on top of a broad thermal wing; the phase transition occurs at the expected photon density and exhibits the predicted dependence on cavity geometry; and the ground-State Mode emerges even for a spatially displaced pump spot. The prospects of the observed effects include studies of extremely weakly interacting low-dimensional Bose gases9 and new coherent ultraviolet sources15.
Ronald A. Sinton - One of the best experts on this subject based on the ideXlab platform.
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Interlaboratory Study of Eddy-Current Measurement of Excess-Carrier Recombination Lifetime
IEEE Journal of Photovoltaics, 2014Co-Authors: Adrienne L. Blum, James S. Swirhun, Ronald A. Sinton, Stanislau Herasimenka, Kevin Lauer, Karsten Bothe, Thomas Roth, Jonas Haunschild, Ziv Hameiri, Bjoern SeipelAbstract:Excess-carrier recombination lifetime is a key parameter in silicon solar cell design and production. With the vast international use and recent standardization (SEMI PV13) of eddy-current wafer and brick silicon lifetime test instruments, it is important to quantify the inter- and intralaboratory repeatability. This paper presents the results of an international interlaboratory study conducted with 24 participants to determine the precision of the SEMI PV13 eddy-current carrier lifetime measurement test method. Overall, the carrier recombination lifetime between-laboratory reproducibility was found to be within ±11% for the quasi-steady-State Mode and ±8% for transient Mode for wafer samples, and within ±4% for bulk samples.
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inter laboratory study of eddy current measurement of excess carrier recombination lifetime
Photovoltaic Specialists Conference, 2013Co-Authors: Adrienne L. Blum, James S. Swirhun, Ronald A. Sinton, Stanislau Herasimenka, Kevin Lauer, Karsten Bothe, Thomas Roth, Jonas Haunschild, Ziv Hameiri, Bjoern SeipelAbstract:Excess-carrier recombination lifetime is a key parameter in silicon solar cell design and production. With the vast international use and recent standardization (SEMI PV13) of eddy-current wafer and brick silicon lifetime test instruments, it is important to quantify the inter- and intralaboratory repeatability. This paper presents the results of an international interlaboratory study conducted with 24 participants to determine the precision of the SEMI PV13 eddy-current carrier lifetime measurement test method. Overall, the carrier recombination lifetime between-laboratory reproducibility was found to be within ±11% for the quasi-steady-State Mode and ±8% for transient Mode for wafer samples, and within ±4% for bulk samples.
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contactless determination of current voltage characteristics and minority carrier lifetimes in semiconductors from quasi steady State photoconductance data
Applied Physics Letters, 1996Co-Authors: Ronald A. Sinton, Andres CuevasAbstract:A simple method for implementing the steady‐State photoconductance technique for determining the minority‐carrier lifetime of semiconductor materials is presented. Using a contactless instrument, the photoconductance is measured in a quasi‐steady‐State Mode during a long, slow varying light pulse. This permits the use of simple electronics and light sources. Despite its simplicity, the technique is capable of determining very low minority carrier lifetimes and is applicable to a wide range of semiconductor materials. In addition, by analyzing this quasi‐steady‐State photoconductance as a function of incident light intensity, implicit current–voltage characteristic curves can be obtained for noncontacted silicon wafers and solar cell precursors in an expedient manner.
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Quasi-steady-State photoconductance, a new method for solar cell material and device characterization
Conference Record of the Twenty Fifth IEEE Photovoltaic Specialists Conference - 1996, 1996Co-Authors: Ronald A. Sinton, Andres Cuevas, M. StuckingsAbstract:This paper describes a new method for minority-carrier lifetime determination using a contactless photoconductance instrument in a quasi-steady-State Mode. Compared to the more common transient photoconductance decay approach, the new technique permits the use of simpler electronics and light sources, yet has the capability to measure lifetimes in the nanosecond to millisecond range. In addition, by analyzing the quasi-steady-State photoconductance as a function of incident light intensity, an implicit I/sub SC/-V/sub OV/ curve can be obtained for noncontacted silicon wafers and solar cell precursors.
Armin G Aberle - One of the best experts on this subject based on the ideXlab platform.
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generalized analysis of quasi steady State and quasi transient measurements of carrier lifetimes in semiconductors
Journal of Applied Physics, 1999Co-Authors: Henning Nagel, Christopher Berge, Armin G AberleAbstract:Recently, a simple yet powerful carrier lifetime technique for semiconductor wafers has been introduced that is based on the simultaneous measurement of the light-induced photoconductance of the sample and the corresponding light intensity [Appl. Phys. Lett. 69, 2510 (1996)]. In combination with a light pulse from a flash lamp, this method allows the injection level dependent determination of the effective carrier lifetime in the quasi-steady-State Mode as well as the quasi-transient Mode. For both cases, approximate solutions (those for steady-State and transient conditions) of the underlying semiconductor equations have been used. However, depending on the actual lifetime value and the time dependence of the flash lamp, specific systematic errors in the effective carrier lifetime arise from the involved approximations. In this work, we present a generalized analysis that avoids these approximations and hence substantially extends the applicability of the quasi-steady-State and quasi-transient methods beyond their previous limits.
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generalized analysis of quasi steady State and quasi transient measurements of carrier lifetimes in semiconductors
Journal of Applied Physics, 1999Co-Authors: Henning Nagel, Christopher Berge, Armin G AberleAbstract:Recently, a simple yet powerful carrier lifetime technique for semiconductor wafers has been introduced that is based on the simultaneous measurement of the light-induced photoconductance of the sample and the corresponding light intensity [Appl. Phys. Lett. 69, 2510 (1996)]. In combination with a light pulse from a flash lamp, this method allows the injection level dependent determination of the effective carrier lifetime in the quasi-steady-State Mode as well as the quasi-transient Mode. For both cases, approximate solutions (those for steady-State and transient conditions) of the underlying semiconductor equations have been used. However, depending on the actual lifetime value and the time dependence of the flash lamp, specific systematic errors in the effective carrier lifetime arise from the involved approximations. In this work, we present a generalized analysis that avoids these approximations and hence substantially extends the applicability of the quasi-steady-State and quasi-transient methods be...
Svetislav Savovic - One of the best experts on this subject based on the ideXlab platform.
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equilibrium Mode distribution and steady State distribution in 100 400 μm core step index silica optical fibers
Applied Optics, 2011Co-Authors: Svetislav Savovic, Alexanda Djordjevich, Ana Simovic, Branko DrljacaAbstract:Using the power flow equation, the State of Mode coupling in 100-400 μm core step-index silica optical fibers is investigated in this article. Results show the coupling length L(c) at which the equilibrium Mode distribution is achieved and the length z(s) of the fiber required for achieving the steady-State Mode distribution. Functional dependences of these lengths on the core radius and wavelength are also given. Results agree well with those obtained using a long-established calculation method. Since large core silica optical fibers are used at short distances (usually at lengths of up to 10 m), the light they transmit is at the stage of coupling that is far from the equilibrium and steady-State Mode distributions.
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equilibrium Mode distribution and steady State distribution in step index glass optical fibers
Acta Physica Polonica A, 2009Co-Authors: Svetislav Savovic, Alexanda Djordjevich, Branko Drljaca, Ana SimovicAbstract:Using the power flow equation, we have examined Mode coupling in a step-index multiMode glass optical fiber. As a result, the coupling length at which the equilibrium Mode distribution is achieved and the length of fiber required for achieving the steady-State Mode distribution are obtained. These lengths are much longer for glass fiber than they are for plastic optical fibers. Our results are in good agreement with experimental results reported earlier.
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numerical solution of the power flow equation in step index plastic optical fibers
Journal of The Optical Society of America B-optical Physics, 2004Co-Authors: Alexanda Djordjevich, Svetislav SavovicAbstract:The numerical solution of the complete power flow equation is reported and employed to investigate the State of Mode coupling along a step-index plastic optical fiber. This solution is based on the explicit finite-difference method and, in contrast to earlier solutions, does not neglect absorption and scattering loss. It is the only solution that can accommodate any input condition throughout the entire range of feasible input angles without the need for restriction to those angles that are sufficiently far away from critical. Our results for the field patterns at different locations along one type of fiber are in agreement with reported measurements earlier. Furthermore, the length of fiber required for achieving a steady-State Mode distribution matches the analytical solution that is available for such distribution as a special case. Mode coupling in plastic fibers is known to affect fiber-optic power delivery, data transmission, and sensing systems.
Jan Klaers - One of the best experts on this subject based on the ideXlab platform.
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bose einstein condensation of photons in an optical microcavity
Nature, 2010Co-Authors: Jan Klaers, Julian Schmitt, Frank Vewinger, Martin WeitzAbstract:Bose–Einstein condensation has been observed in several physical systems, but is not predicted to occur for blackbody radiation such as photons. However, it becomes theoretically possible in the presence of thermalization processes that conserve photon number. Martin Weitz and colleagues have now realized such conditions experimentally, observing Bose–Einstein condensation of photons in a dye-filled optical microcavity. The effect is of interest for fundamental studies and may lead to new coherent ultraviolet sources. Bose–Einstein condensation has been observed in several physical systems, but is not predicted to occur for blackbody radiation such as photons. However, it becomes theoretically possible in the presence of thermalization processes that conserve photon number. These authors experimentally realise such conditions, observing Bose–Einstein condensation of photons in a dye-filled optical microcavity. The effect is of interest for fundamental studies and may lead to new coherent ultraviolet sources. Bose–Einstein condensation (BEC)—the macroscopic ground-State accumulation of particles with integer spin (bosons) at low temperature and high density—has been observed in several physical systems1,2,3,4,5,6,7,8,9, including cold atomic gases and solid-State quasiparticles. However, the most omnipresent Bose gas, blackbody radiation (radiation in thermal equilibrium with the cavity walls) does not show this phase transition. In such systems photons have a vanishing chemical potential, meaning that their number is not conserved when the temperature of the photon gas is varied10; at low temperatures, photons disappear in the cavity walls instead of occupying the cavity ground State. Theoretical works have considered thermalization processes that conserve photon number (a prerequisite for BEC), involving Compton scattering with a gas of thermal electrons11 or photon–photon scattering in a nonlinear resonator configuration12,13. Number-conserving thermalization was experimentally observed14 for a two-dimensional photon gas in a dye-filled optical microcavity, which acts as a ‘white-wall’ box. Here we report the observation of a Bose–Einstein condensate of photons in this system. The cavity mirrors provide both a confining potential and a non-vanishing effective photon mass, making the system formally equivalent to a two-dimensional gas of trapped, massive bosons. The photons thermalize to the temperature of the dye solution (room temperature) by multiple scattering with the dye molecules. Upon increasing the photon density, we observe the following BEC signatures: the photon energies have a Bose–Einstein distribution with a massively populated ground-State Mode on top of a broad thermal wing; the phase transition occurs at the expected photon density and exhibits the predicted dependence on cavity geometry; and the ground-State Mode emerges even for a spatially displaced pump spot. The prospects of the observed effects include studies of extremely weakly interacting low-dimensional Bose gases9 and new coherent ultraviolet sources15.
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bose einstein condensation of photons in an optical microcavity
Nature, 2010Co-Authors: Jan Klaers, Julian Schmitt, Frank Vewinger, Martin WeitzAbstract:Bose–Einstein condensation has been observed in several physical systems, but is not predicted to occur for blackbody radiation such as photons. However, it becomes theoretically possible in the presence of thermalization processes that conserve photon number. Martin Weitz and colleagues have now realized such conditions experimentally, observing Bose–Einstein condensation of photons in a dye-filled optical microcavity. The effect is of interest for fundamental studies and may lead to new coherent ultraviolet sources. Bose–Einstein condensation has been observed in several physical systems, but is not predicted to occur for blackbody radiation such as photons. However, it becomes theoretically possible in the presence of thermalization processes that conserve photon number. These authors experimentally realise such conditions, observing Bose–Einstein condensation of photons in a dye-filled optical microcavity. The effect is of interest for fundamental studies and may lead to new coherent ultraviolet sources. Bose–Einstein condensation (BEC)—the macroscopic ground-State accumulation of particles with integer spin (bosons) at low temperature and high density—has been observed in several physical systems1,2,3,4,5,6,7,8,9, including cold atomic gases and solid-State quasiparticles. However, the most omnipresent Bose gas, blackbody radiation (radiation in thermal equilibrium with the cavity walls) does not show this phase transition. In such systems photons have a vanishing chemical potential, meaning that their number is not conserved when the temperature of the photon gas is varied10; at low temperatures, photons disappear in the cavity walls instead of occupying the cavity ground State. Theoretical works have considered thermalization processes that conserve photon number (a prerequisite for BEC), involving Compton scattering with a gas of thermal electrons11 or photon–photon scattering in a nonlinear resonator configuration12,13. Number-conserving thermalization was experimentally observed14 for a two-dimensional photon gas in a dye-filled optical microcavity, which acts as a ‘white-wall’ box. Here we report the observation of a Bose–Einstein condensate of photons in this system. The cavity mirrors provide both a confining potential and a non-vanishing effective photon mass, making the system formally equivalent to a two-dimensional gas of trapped, massive bosons. The photons thermalize to the temperature of the dye solution (room temperature) by multiple scattering with the dye molecules. Upon increasing the photon density, we observe the following BEC signatures: the photon energies have a Bose–Einstein distribution with a massively populated ground-State Mode on top of a broad thermal wing; the phase transition occurs at the expected photon density and exhibits the predicted dependence on cavity geometry; and the ground-State Mode emerges even for a spatially displaced pump spot. The prospects of the observed effects include studies of extremely weakly interacting low-dimensional Bose gases9 and new coherent ultraviolet sources15.
