Vertical motional narrowing of exciton polaritons in GaN based multiple quantum wells

Malpuech, Guillaume; Kavokin, Alexey

doi:10.1063/1.126575

Cited by 9 publications

(8 citation statements)

References 11 publications

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“…Both "bright" modes and disorder scattering dominate at very early times (less than 500 fs), while at longer times the remaining part of the coherent optical signal comes from the ensemble of "dark" modes populated because of light-scattering from "bright" modes. Consideration of two branches of "dark" modes yields the following approximative formula for the decay-rate of time-resolved transmission [7]:…”

Section: Resultsmentioning

confidence: 99%

“…The disorder arises mainly due to random polarization fields [3,4] and is manifested by a huge Stokes-shift and inhomogeneous broadening of the exciton lines. Recently, it has been shown experimentally [5] and theoretically [6,7] that the radiative coupling between excitons confined in different QWs in multiple quantum well (MQW) structures may reduce effectively the disorder effect on the exciton. This effect known as the vertical motional narrowing (VMN) effect manifests itself in the increase of the decay-time of the time-resolved reflection signal from MQWs as a function of the number of wells.…”

Section: Introductionmentioning

confidence: 99%

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Propagation and Scattering of Exciton-Polaritons in Nitride-Based Multiple Quantum Wells

et al. 2000

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We show theoretically that disorder-induced scattering of light between « bright » and « dark » exciton-polariton modes governs the coherent optical response of GaN/AlGaN quantum wells (QWs) on a femtosecond scale. The incident light essentially excites the "bright" modes, they emit the most part of light radiatively during first few hundreds of femtoseconds. The rest of the coherent signal, i.e. the temporal behaviour on a scale from 1 to few picoseconds, comes from the "dark" modes, populated due to the elastic scattering processes in the system, and mixed so that they form two bulk-like polariton branches. The pico-second scale optical response of GaN/AlGaN QWs is essentially incoherent because of a very efficient scattering of exciton-polaritons by a structural disorder. INTRODUCTIONRandom potential fluctuations strongly affect the confined exciton states in GaN/AlGaN and GaN/InGaN quantum wells (QWs) thus reducing the advantages of these structures for opto-electronics applications [1,2]. The disorder arises mainly due to random polarization fields [3,4] and is manifested by a huge Stokes-shift and inhomogeneous broadening of the exciton lines. Recently, it has been shown experimentally [5] and theoretically [6,7] that the radiative coupling between excitons confined in different QWs in multiple quantum well (MQW) structures may reduce effectively the disorder effect on the exciton. This effect known as the vertical motional narrowing (VMN) effect manifests itself in the increase of the decay-time of the time-resolved reflection signal from MQWs as a function of the number of wells. It results from the averaging of the disorder potential in a MQW structure by extended exciton-polariton modes that occupy entire the structure.The interplay between exciton-polaritons and potential disorder is a subject of our present study. We analyze the behavior of polariton eigen-modes in MQWs as a function of exciton inhomogeneous broadening, and compare it with calculated frequency-and timeresolved transmission spectra. The total number of exciton-polariton eigen-modes in a system of N QWs equals N. One can distinguish between "bright" polariton modes whose oscillator strength exceeds the single-QW exciton oscillator strength 0 Γ and "dark" polariton modes

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Propagation and Scattering of Exciton-Polaritons in Nitride-Based Multiple Quantum Wells

et al. 2000

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“…The values for the inhomogeneous (5 meV), homogeneous (0.1 meV), and radiative broadening (0.4 meV) in GaN quantum wells were taken from Ref. 37. (Color online) Variation in the reflected intensity (contours) and phase (color scale) of the system with E 1 and E 2 .…”

Section: Methodsmentioning

confidence: 99%

Holographic arrays based on semiconductor microstructures

Liew¹

2012

Phys. Rev. B

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A concept of complex reflectivity modulation is proposed based on the electrical control of quantum well exciton resonances that influence the propagation of light in a layered semiconductor structure. By variation in exciton energies, both the intensity and the phase of reflected light can be fully controlled. Unlike previous devices, for full complex light modulation, the design is based on a single device in a single structure. The device allows complete 100% intensity contrast and allows for the construction of small pixel sizes with fast response times.

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“…This makes GaN and related heterostructures quite promising for study of light-exciton coupling phenomena (like the polariton effect [5], motional narrowing [6], resonant Rayleigh scattering [7], etc.). However, quite often, GaN-based quantum wells (QWs) exhibit relatively weak exciton resonances, while usually the quantum confinement leads to a significant increase of the oscillator strength.…”

Section: Introductionmentioning

confidence: 99%

Experimental and Theoretical Tools for the Study of Exciton Properties versus Disorder in Nitride-Based Quantum Structures

Gil

Zamfirescu

Bigenwald

et al. 2001

phys. stat. sol. (b)

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We show that resonant Rayleigh scattering measurements combined with conventional reflectivity measurements can easily allow the determination of the most relevant parameters of nitride-based quantum well excitons. In particular, comparing the Fourier-transformed reflection spectra with calculated time-resolved reflectivities, we have found the exciton oscillator strength to decrease dramatically with increase of the QW width in the GaN/Al 0.07 Ga 0.93 N system. The collapse of the oscillator strength is a manifestation of the polarization field effect, as confirmed by our variational calculation. We find that only excitons in very thin quantum wells have an oscillator strength exceeding that of the exciton in bulk GaN.

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Vertical motional narrowing of exciton polaritons in GaN based multiple quantum wells

Cited by 9 publications

References 11 publications

Propagation and Scattering of Exciton-Polaritons in Nitride-Based Multiple Quantum Wells

Propagation and Scattering of Exciton-Polaritons in Nitride-Based Multiple Quantum Wells

Holographic arrays based on semiconductor microstructures

Experimental and Theoretical Tools for the Study of Exciton Properties versus Disorder in Nitride-Based Quantum Structures

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