Charge-transfer-induced optical bistability in an asymmetric quantum-well structure

Seto, M.; Helm, M.

doi:10.1063/1.106511

Cited by 38 publications

(12 citation statements)

References 12 publications

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“…Intrinsic OB was studied in Ref. 29 in a similar setting to ours, but in their model they neglected depolarization shift and coherence effects ͑since they used only a rate-equation model͒; these two ingredients though are essential for the OB observed here. Two other studies 13,30 proposed density-matrix models describing the intrinsic OB of n-doped QW's, but they were both limited to the RWA and they did not verify the applicability range of their results.…”

Section: A Optical Bistability In the Two-subband Qwmentioning

confidence: 99%

Nonlinear dynamics in far-infrared driven quantum-well intersubband transitions

et al. 2002

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We study the effect of many-body interactions on the collective response of confined electrons in doped quantum-well ͑QW͒ heterostructures to intense far-infrared radiation. Absorption line shapes are computed both by numerically integrating the equations of motion and by using the appropriately time-averaged equations. For a two-subband double-QW system, optical bistability and period-doubling bifurcations are observed and their parameter range of activity is given. For a three-subband asymmetric triple-QW system driven at ϷE 2 ϪE 0 , Hopf bifurcations occur which generate a strong response at a frequency incommensurate with the drive frequency or any natural frequency of the system.

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Section: A Optical Bistability In the Two-subband Qwmentioning

confidence: 99%

Nonlinear dynamics in far-infrared driven quantum-well intersubband transitions

et al. 2002

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“…We describe here a type-II quantum well stucture which exhibits an intrinsic optical bistability on photoluminescence (PL). The most outstanding point is that, because of photocreated electric fields, it is observable without any external voltage bias, contrary to all other electrooptic bistable devices like self electrooptic effect devices (SEED) [5], double-barrier resonant-tunnelling stuctures [6] or asymmetric quantum wells [7][8][9]. However, electrical detection and switchings are also possible.…”

mentioning

confidence: 99%

Optical Bistability Due to Photo-Induced Charge Transfer in a Type-II GaAs/AlAs Quantum Well

Teissier¹,

Planel²

1992

Acta Phys. Pol. A

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We present a bistability of low temperature photoluminescence in a n-i-n type-II GaAs/AlAs quantum heterostructure. Spectral analysis and electrical measurements indicate that the two states correspond to hole accumulation in different layers. The transition occurs with the alignment of electronic Γ and Χ states due to optical pumping, and no external voltage bias is needed.PACS numbers: 78.55. Cr, 42.65.Ρc, 72.20.7v The feasibility of type-ΙΙ GaAs/AlAs heterostructures involving X-point conduction states has motivated several studies since 1986 [1][2][3]. In an asymmetric stucture, the creation of internal electric fields due to spatial separation of charges has been demonstrated [4]. We describe here a type-II quantum well stucture which exhibits an intrinsic optical bistability on photoluminescence (PL). The most outstanding point is that, because of photocreated electric fields, it is observable without any external voltage bias, contrary to all other electrooptic bistable devices like self electrooptic effect devices (SEED) [5], double-barrier resonant-tunnelling stuctures [6] or asymmetric quantum wells [7][8][9]. However, electrical detection and switchings are also possible.The stucture grown by molecular beam epitaxy consists of a n-i-n sequence. The intrinsic region is made of four layers, as described and labelled in Fig. 1. It may be viewed as a type-II quantum well, embedded into a Ga0.65Al0.35Αs layer acting as a barrier for Γ-or X-electrons. The electron ground level is of Xxy symmetry [10] and located in the AlAs layer, whereas the hole ground state is of Γ symmetry and located in the GaAs layer. The Γ-symmetry conduction level located in the GaAs layer is about 60 meV. above the Χ ground state. For electrical measurements under optical excitation, we have made 300 x 300 µm mesa-type diodes with a peripheric Au-Ge-Ni ohmic contact by conventional lithography and chemical etching.The PL spectra, obtained with an Argon-laser excitation, show two main lines (Fig. 2): the one (at about 1.80 eV) is attributed to recombination in the type-II well, the other (at about 2.00 eV) to recombination in the GaAlAs barriers. When the n-i-n diode is short-circuited (either by the external contacts in (656)

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“…8,9 Inspired by the photoabsorption experiments by Craig et al, 4 this letter presents a theoretical study of the optical bistability region in a strongly driven, modulation n-doped GaAs/Al 0.3 Ga 0.7 As quantum well. We demonstrate that ISB bistability can be manipulated on a picosecond time scale by short THz control pulses.…”

mentioning

confidence: 99%

“…1 Many ISB effects of practical interest occur in the nonlinear regime, such as second-and third-harmonic generation, 2 intensitydependent saturation of photo-absorption, 3,4 directional control over photocurrents, 5 generation of ultrashort THz pulses, 6 plasma instability, 7 or optical bistability. 8,9 Inspired by the photoabsorption experiments by Craig et al, 4 this letter presents a theoretical study of the optical bistability region in a strongly driven, modulation n-doped GaAs/Al 0.3 Ga 0.7 As quantum well. We demonstrate that ISB bistability can be manipulated on a picosecond time scale by short THz control pulses.…”

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confidence: 99%

Coherent control of intersubband optical bistability in quantum wells

Wijewardane

Ullrich

2004

Applied Physics Letters

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We present a study of the nonlinear intersubband ͑ISB͒ response of conduction electrons in a GaAs/Al 0.3 Ga 0.7 As quantum well to strong terahertz ͑THz͒ radiation, using a density-matrix approach combined with time-dependent density-functional theory. We demonstrate coherent control of ISB optical bistability, using THz control pulses to induce picosecond switching between the bistable states. The switching speed is determined by the ISB relaxation and decoherence times, T 1 and T 2 . © 2004 American Institute of Physics. ͓DOI: 10.1063/1.1751611͔Intersubband ͑ISB͒ transitions in semiconductor quantum wells take place on a meV energy scale and are therefore attractive for terahertz ͑THz͒ device applications.1 Many ISB effects of practical interest occur in the nonlinear regime, such as second-and third-harmonic generation, 2 intensitydependent saturation of photo-absorption, 3,4 directional control over photocurrents, 5 generation of ultrashort THz pulses, 6 plasma instability, 7 or optical bistability. 8,9 Inspired by the photoabsorption experiments by Craig et al., 4 this letter presents a theoretical study of the optical bistability region in a strongly driven, modulation n-doped GaAs/Al 0.3 Ga 0.7 As quantum well. We demonstrate that ISB bistability can be manipulated on a picosecond time scale by short THz control pulses. This opens up opportunities for experimental study of optical bistability, which in the long run may lead to THz applications such as high-speed alloptical modulators and switches.Most previous theoretical studies of nonlinear ISB dynamics were based on density-matrix approaches, in Hartree approximation 10-12 or using exchange-only semiconductor Bloch equations. [13][14][15] These studies showed that the collective ISB electron dynamics is strongly influenced by depolarization and exchange-correlation ͑xc͒ many-body effects. 15 We will account for these effects using timedependent density-functional theory, which has the advantage of formal and computational simplicity.We describe the conduction subbands in effective-mass approximation, where m*ϭ0.067m and e*ϭe/ͱ⑀, ⑀ϭ13, are the effective mass and charge for GaAs. Initially, the conduction electrons are in the ground state, characterized by single-particle states of the form ⌿ jq ʈ 0 (r) ϭA Ϫ1/2 e iq ʈ r ʈ j 0 (z), with r ʈ and q ʈ in the x -y plane. The envelope function for the jth subband j 0 (z) follows selfconsistently from a one-dimensional Kohn-Sham ͑KS͒ equation, 16 with the ground-state densityHere, E jq ʈ ϭ j ϩប 2 q ʈ 2 /2m*, and j and F are the subband and Fermi energy levels. We choose the electronic sheet density N s such that only the lowest subband is occupied, in which case F ϭប 2 N s /m*ϩ 1 . Under the influence of THz driving fields, linearly polarized along z, the time-dependent states have the form ⌿ jq ʈ (r,t)ϭA Ϫ1/2 e iq ʈ r ʈ j (z,t), with initial condition ⌿ jq ʈ (r,t 0 )ϭ⌿ jq ʈ 0 (r). In the absence of disorder and phonons, the time evolution of the envelope functions follows from a time-dependent KS equationHer...

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Charge-transfer-induced optical bistability in an asymmetric quantum-well structure

Cited by 38 publications

References 12 publications

Nonlinear dynamics in far-infrared driven quantum-well intersubband transitions

Nonlinear dynamics in far-infrared driven quantum-well intersubband transitions

Optical Bistability Due to Photo-Induced Charge Transfer in a Type-II GaAs/AlAs Quantum Well

Coherent control of intersubband optical bistability in quantum wells

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