Picosecond ultrasonics study of metallic multilayers

Perrin, Bernard; Bonello, Bernard; Jeannet, J. C.; Romatet, E.

doi:10.1016/0921-4526(95)00852-7

Cited by 66 publications

(62 citation statements)

References 6 publications

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“…In contrast, for example, Michelson or Mach-Zehnder interferometers are more sensitive to mechanical noise and require an active stabilization or a modulation technique. 22,[25][26][27] Sagnac interferometers based on fiber optics have previously been successfully used to monitor bulk ultrasonic waves in the megahertz frequency range. [28][29][30][31] The inherently passive Sagnac interferometers presented here can be used for measuring or imaging small changes in optical reflectivity or phase over a wide frequency range up to 1 THz or above.…”

Section: A Optical Interferometermentioning

confidence: 99%

Scanning ultrafast Sagnac interferometry for imaging two-dimensional surface wave propagation

Tachizaki

Muroya

Matsuda

et al. 2006

Review of Scientific Instruments

139

110

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We describe an improved two-dimensional optical scanning technique combined with an ultrafast Sagnac interferometer for delayed-probe imaging of surface wave propagation. We demonstrate the operation of this system, which involves the use of a single focusing objective, by monitoring surface acoustic wave propagation on opaque substrates with picosecond temporal and micron lateral resolutions. An improvement in the lateral resolution by a factor of 3 is achieved in comparison with previous setups for similar samples.

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Section: A Optical Interferometermentioning

confidence: 99%

Scanning ultrafast Sagnac interferometry for imaging two-dimensional surface wave propagation

Tachizaki

Muroya

Matsuda

et al. 2006

Review of Scientific Instruments

139

110

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“…The setup used in our study follows the classical scheme of picosecond acoustics. 14,15,21,22 In the particular case of our study, the BFO sample is excited by a UV pump beam with 3.1 eV photon energy (see inset of Fig. 1).…”

mentioning

confidence: 99%

Photoexcitation of gigahertz longitudinal and shear acoustic waves in BiFeO3 multiferroic single crystal

Ruello

Pézeril

Avanesyan

et al. 2012

Applied Physics Letters

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Using femtosecond laser pulses, coherent GHz acoustic phonons are efficiently photogenerated and photodetected in BiFeO3 (BFO) multiferroic single crystal. Due to the crystal lattice symmetry, longitudinal as well as two transverse acoustic modes are generated and detected, and the corresponding sound velocities are determined. This provides the opportunity to experimentally evaluate the elastic coefficients of the multiferroic compound BiFeO3 that have been estimated so far only through ab initio calculations. The knowledge of the elastic properties of BFO is highly desired for BFO integration in nanoelectronic devices. Moreover, our findings highlight also that BFO may be a good candidate for light-controlled coherent acoustic phonons sources.

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“…7 Despite this fundamental and practical interest previous laser picosecond acoustics experiments with semiconductor thin films involved complex GaAs multilayer geometries, and were not designed for the investigation of carrier diffusion. [10][11][12][13] There are several challenging experimental problems related to such studies of carrier diffusion in crystalline semiconductors on picosecond timescales. First one must overcome the dual requirement for a sample of micron order or less in thickness ͑to avoid significant acoustic propagation distortion͒ and for an acoustically mismatched substrate ͑to allow significant echo amplitudes to be obtained͒.…”

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Ultrafast carrier diffusion in gallium arsenide probed with picosecond acoustic pulses

et al. 2001

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We describe an experimental investigation of the generation and detection of picosecond acoustic-phonon pulses in a thin slab of GaAs using ultrashort optical pulses. Comparison of the optical phase variation with a simple theory for ambipolar diffusion indicates that carrier diffusion has a significant effect on the shape of the phonon pulses generated. The phonon pulse duration is measured to be ϳ25 ps, four times longer than that expected from optical-absorption considerations alone, indicating that hot carriers penetrate more than 100 nm into the sample during the phonon pulse generation process. DOI: 10.1103/PhysRevB.64.081202 PACS number͑s͒: 73.50.Ϫh, 43.35.ϩd, 62.65.ϩk Ultrafast carrier diffusion in semiconductors has been studied by a variety of experimental techniques. Ultrashort pulse optical pump and probe methods based on the measurement of optical reflectivity, electro-optic sampling or luminescence, including near-field methods, have been applied to the measurement of diffusion of hot carriers in bulk semiconductors and quantum nanostructures in the lateral or through-thickness directions.1-4 The detection principle in this case involves the coupling of the carriers to the electric field of the optical wave. Optical pump and probe methods can also exploit the coupling of the carriers to strain, and can be used to monitor carrier diffusion from the shape of the acoustic-phonon pulses generated, a technique that involves the pulse-echo methods of laser picosecond acoustics. 5,6 The penetration of hot carriers perpendicular to metal surfaces when excited with an ultrashort optical pulse has been shown to broaden the phonon pulses generated.7 Laser acoustics studies with nanosecond or sub-nanosecond temporal resolution in crystalline Ge and Cd x S 1Ϫx Se have demonstrated that carrier diffusion similarly affects acoustic generation in semiconductors. 8,9 However, there have been no studies of the effect of carrier diffusion on acoustic generation in semiconductors with picosecond time resolution. This is unfortunate in view of the pressing need for such studies to support industrial development in quantitative nondestructive evaluation of integrated circuits or semiconductor nanostructures. There are also possible applications in the field of GHz-THz acousto-optic modulation in ultrahigh speed semiconductor devices. Moreover, probing carrier diffusion on ultrashort timescales from acoustic measurements provides an interesting perspective on the time-and space-dependent nonequilibrium carrier distribution, because it allows depth profiling of the carrier penetration into the bulk.7 Despite this fundamental and practical interest previous laser picosecond acoustics experiments with semiconductor thin films involved complex GaAs multilayer geometries, and were not designed for the investigation of carrier diffusion. [10][11][12][13] There are several challenging experimental problems related to such studies of carrier diffusion in crystalline semiconductors on picosecond timescales. First one must ove...

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Picosecond ultrasonics study of metallic multilayers

Cited by 66 publications

References 6 publications

Scanning ultrafast Sagnac interferometry for imaging two-dimensional surface wave propagation

Scanning ultrafast Sagnac interferometry for imaging two-dimensional surface wave propagation

Photoexcitation of gigahertz longitudinal and shear acoustic waves in BiFeO3 multiferroic single crystal

Ultrafast carrier diffusion in gallium arsenide probed with picosecond acoustic pulses

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