Ultrafast polarization dynamics in biased quantum wells under strong femtosecond optical excitation

Turchinovich, Dmitry; Jepsen, Peter Uhd; Monozon, B. S.; Koch, Martin; Lahmann, S.; Rossów, U.; Hangleiter, A.

doi:10.1103/physrevb.68.241307

Cited by 60 publications

(67 citation statements)

References 13 publications

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“…These parameters are typical for the frequency-doubled Ti:sapphire regenerative amplifier used in our experiments on ultrafast optical screening of InGaN / GaN QWs. 12 In Figs. 2-4 the temporal evolution of the empty wave functions and the temporal and spatial profile of the e-h density creation rates are shown for a QW with a bias field of 3 MV/ cm and L z = 2.5 nm, which is subject to excitation at various pump fluences. The wave functions and e-h density creation rate dynamics clearly differ in dependence on the pump fluence.…”

Section: Resultsmentioning

confidence: 99%

“…These QW parameters are typical for wurtzite InGaN / GaN QWs experimentally studied in the literature. 7,8,12,19 Interestingly, the dependencies of the resulting Stark shifts and effective bias fields in the QWs on the pump fluence ͓see Figs. 6͑a͒, 6͑b͒, 7͑a͒, and 7͑b͔͒ do not always show unambiguous trend with the initial potential drop across the QW ͑and therefore the initial wave-function separation͒.…”

Section: Resultsmentioning

confidence: 99%

“…This polarization change will lead to the emission of an electromagnetic field transient with terahertz frequency content, thus releasing the electrostatic energy initially stored in the biased QW, which is a nanoscale capacitor. 12 The temporal evolution of the electric field of the terahertz transient in the far field is given by the second temporal derivative of the induced polarization ͑see, for example, Refs. 15 and 21͒.…”

Section: Resultsmentioning

confidence: 99%

“…12,20 Any other more elaborate ͑and therefore more resource consuming͒ approach to calculate the band structure of the QW in the presence of screening charges ͑see, for example, Refs. 10, 11, and 16͒ can be used within the main frame of our model.…”

Section: Discussionmentioning

confidence: 99%

“…12 In this pro-cess the electrostatic energy stored in the nanoscale capacitor is released in the form of an electromagnetic field transient due to the ultrafast polarization change. If the dynamical screening occurs on a femtosecond time scale then the spectral content of the transient will belong to the terahertz range.…”

Section: Introductionmentioning

confidence: 99%

See 4 more Smart Citations

Role of dynamical screening in excitation kinetics of biased quantum wells: Nonlinear absorption and ultrabroadband terahertz emission

Turchinovich

Monozon

Jepsen

2006

Journal of Applied Physics

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In this work we describe the ultrafast excitation kinetics of a biased quantum well, arising from the optically induced dynamical screening of a bias electric field. The initial bias electric field inside the quantum well is screened by the optically excited polarized electron-hole pairs. This leads to a dynamical modification of the properties of the system within an excitation pulse duration. We calculate the excitation kinetics of a biased quantum well and the dependency of resulting electronic and optical properties on the excitation pulse fluence, quantum well width, and initial bias field strength. Our calculations, in particular, predict the strongly nonlinear dependency of the effective optical absorption coefficient on the excitation pulse fluence, and ultrabroadband terahertz emission. Our theoretical model is free of fitting parameters. Calculations performed for internally biased InGaN / GaN quantum wells are in good agreement with our experimental observations ͓Turchinovich et al., Phys. Rev. B 68, 241307͑R͒ ͑2003͔͒, as well as in perfect compliance with qualitative considerations.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Role of dynamical screening in excitation kinetics of biased quantum wells: Nonlinear absorption and ultrabroadband terahertz emission

Turchinovich

Monozon

Jepsen

2006

Journal of Applied Physics

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Ultrafast Terahertz Nanoseismology of GaInN/GaN Multiple Quantum Wells

Mannan

Bagsican

Yamahara

et al. 2021

Advanced Optical Materials

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Terahertz (THz) emission spectroscopy and microscopy are applied to investigate the electron and lattice dynamics of Ga0.8In0.2N/GaN multiple quantum wells (MQWs). The THz emission consists of three distinct, differently timed signals, whose physical mechanisms are attributed to i) laser‐induced ultrafast dynamical screening of built‐in bias electric field in MQWs followed by ii) capacitive charge oscillation of the excited carriers and iii) the coherent acoustic phonon (CAP)‐driven polarization surge at the discontinuity between the GaN capping layer and air. These multifunctional optical responses show strong dependence on the quantum well width and photon energies. The temporal separation between the first and third THz pulses corresponds to the propagation of the CAP across the GaN capping layer of the MQW structure, whose thickness can thus be determined with 10 nm precision.

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InGaN/GaN dot‐in‐a‐wire: ultimate terahertz nanostructure

Sun

Chen

Ding

et al. 2015

Laser & Photonics Reviews

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The terahertz (THz) radiation from InGaN/GaN dot‐in‐a‐wire nanostructures has been investigated. A submicrowatt THz signal is generated with just ten vertically stacked InGaN quantum dots (QDs) in each GaN nanowire. Based on the experimental results and analysis, a single quantum wire is expected to generate an output power as high as 10 pW, corresponding to 1 pW per dot. These structures are among the most efficient three‐dimensional quantum‐confined nanostructures for the THz emission. By applying a reverse bias along the wires in a light‐emitting device (LED) consisting of such nanostructures, the THz output power is increased more than fourfold. Based on THz and photoluminescence (PL) experiments, the mechanism for the THz emission is attributed to dipole radiation induced by internal electric fields and enhanced by external fields.

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Ultrafast polarization dynamics in biased quantum wells under strong femtosecond optical excitation

Cited by 60 publications

References 13 publications

Role of dynamical screening in excitation kinetics of biased quantum wells: Nonlinear absorption and ultrabroadband terahertz emission

Role of dynamical screening in excitation kinetics of biased quantum wells: Nonlinear absorption and ultrabroadband terahertz emission

Ultrafast Terahertz Nanoseismology of GaInN/GaN Multiple Quantum Wells

InGaN/GaN dot‐in‐a‐wire: ultimate terahertz nanostructure

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