Raman-Brillouin light scattering in low-dimensional systems: Photoelastic model versus quantum model

Mlayah, Adnen; Huntzinger, Jean-Roch; Large, Nicolas

doi:10.1103/physrevb.75.245303

Cited by 11 publications

(6 citation statements)

References 34 publications

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“…Previously the confined modes in thin Si membranes have been observed in static Brillouin scattering experiments. However, the lifetimes of these modes could not be inferred due to a limited frequency resolution [27][28][29]. The fundamental mode at 19.15 GHz with harmonics up to the 19th order were measured with frequencies up to nearly 300 GHz.…”

Section: Silicon Membranesmentioning

confidence: 99%

Generation and detection of gigahertz acoustic oscillations in thin membranes

Schubert

Großmann

et al. 2015

Ultrasonics

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Section: Silicon Membranesmentioning

confidence: 99%

Generation and detection of gigahertz acoustic oscillations in thin membranes

Schubert

Großmann

et al. 2015

Ultrasonics

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“…These effects have been studied via continuous wave light scattering techniques such as Brillouin and Raman scattering in supported and free-standing thin films. [5][6][7][8][9] Recently time-resolved experiments have contributed significantly to the understanding of phonon dynamics in nanoscale systems and nanoparticles. 4,[10][11][12][13] In this Rapid Communication we present results of femtosecond time-resolved pump-probe experiments performed on free-standing Si membranes with a thickness of a few hundred nanometers.…”

mentioning

confidence: 99%

Confined longitudinal acoustic phonon modes in free-standing Si membranes coherently excited by femtosecond laser pulses

et al. 2009

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In this Rapid Communication we report the first time-resolved measurements of confined acoustic phonon modes in free-standing Si membranes excited by fs laser pulses. Pump-probe experiments using asynchronous optical sampling reveal the impulsive excitation of discrete acoustic modes up to the 19th harmonic order for membranes of two different thicknesses. The modulation of the membrane thickness is measured with fm resolution. The experimental results are compared with a theoretical model including the electronic deformation potential and thermal stress for the generation mechanism. The detection is modeled by the photoelastic effect and the thickness modulation of the membrane, which is shown to dominate the detection process. The lifetime of the acoustic modes is found to be at least a factor of 4 larger than that expected for bulk Si.Free-standing thin semiconductor membranes have a wide range of applications, for example, as key elements in nanomechanical systems, 1 sensors, 2 or optomechanical systems. 3 Thorough understanding of the mechanical and elastic properties in these structures is crucial for the design and engineering of the desired performance of these potential devices. 4 When the dimension of these structures is reduced to the order of magnitude of the phonon wavelength, the confinement of acoustic modes leads to a discretization of the acoustic spectrum. These effects have been studied via continuous wave light scattering techniques such as Brillouin and Raman scattering in supported and free-standing thin films. 5-9 Recently time-resolved experiments have contributed significantly to the understanding of phonon dynamics in nanoscale systems and nanoparticles. 4,[10][11][12][13] In this Rapid Communication we present results of femtosecond time-resolved pump-probe experiments performed on free-standing Si membranes with a thickness of a few hundred nanometers. A superposition of oscillations corresponding to frequencies of a fundamental mode and its higher odd harmonics up to the 19th order with lifetimes exceeding 1 ns is observed in the time domain. The results are successfully modeled using a combined elastic and electromagnetic model. It is shown that the detection process is dominated by the dynamic change in the membrane thickness. Our analysis demonstrates that free-standing Si membranes are a model system, which allows disentanglement of basic phonon-photon interaction processes.The pump-probe experiments were performed using highspeed asynchronous optical sampling ͑ASOPS͒ described in detail before. 14 Two femtosecond Ti:Sapphire oscillators are used to generate the pump and probe pulses with a duration of less than 100 fs. The repetition rates f rep of about 800MHz are stabilized in order to fix the difference of the repetition rates at ⌬f rep = 10 kHz. This offset allows for an automatic scan of the measurement window ͑f rep −1 = 1.2 ns͒ by the probe pulse in ⌬f rep −1 = 100 s without mechanical delay line. The time resolution achieved by this technique lies below 150 fs. Experiment...

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“…͑3͒ reduces to one dominant term and the RB peak frequencies and intensities are directly related to the spatial distribution of the electronic density selected by the optical excitation. 16 When considering a large collection of intermediate states, summation of the scattering amplitudes in Eq. ͑3͒ leads to strong interferences in the overall RB intensity.…”

Section: B Quantum Model-raman-brillouin Electronic Densitymentioning

confidence: 99%

“…As discussed in Ref. 16, the RBED is the link between the Raman-Brillouin quantum model and the photoelastic model.…”

Section: B Quantum Model-raman-brillouin Electronic Densitymentioning

confidence: 99%

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Raman-Brillouin electronic density in short-period superlattices

et al. 2010

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We analyze and interpret resonant Raman-Brillouin scattering by folded acoustic vibrations in short-period GaAs/AlAs superlattices. Analysis of the spectra and their resonance behavior is performed using a RamanBrillouin electronic density constructed by combining thousands transitions between electronic eigenstates of the system according to their weight in the light-scattering process. We show that plots of this effective electronic density allow for capturing the essential physics of the electron-phonon interaction and of the resonant light-scattering process in a situation where complex effects are simultaneously present: electronic confinement in the quantum wells and wave-function delocalization due to interlayer coupling, folding of acoustic dispersion and symmetry changes in the deformation fields, resonant selection of optical transitions. Comparison between the measured spectra and those simulated using the Raman-Brillouin quantum model and the photoelastic model are presented. Activation and/or deactivation of the scattering by acoustic vibration doublets and changes in their intensity ratio with excitation energy are directly related to the Raman-Brillouin electronic density distribution along the superlattices axis. Limitations of the photoelastic model are discussed by comparing the steplike variation in the photoelastic coefficient to the Raman-Brillouin electronic density profiles.

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Raman-Brillouin light scattering in low-dimensional systems: Photoelastic model versus quantum model

Cited by 11 publications

References 34 publications

Generation and detection of gigahertz acoustic oscillations in thin membranes

Generation and detection of gigahertz acoustic oscillations in thin membranes

Confined longitudinal acoustic phonon modes in free-standing Si membranes coherently excited by femtosecond laser pulses

Raman-Brillouin electronic density in short-period superlattices

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