Optical control of coherent optical phonons in bismuth films

Hase, Muneaki; Mizoguchi, K.; Harima, Hiroshi; Nakashima, S.; Tani, Masahiko; Sakai, Kiyomi; Hangyo, Masanori

doi:10.1063/1.117502

Cited by 208 publications

(151 citation statements)

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“…Moreover, excitation with multiple pump pulses provides a means to coherently control SAP oscillations. This approach is similar to earlier studies involving coherent control of bulk optical and acoustic phonon oscillations 10,11 .…”

supporting

confidence: 51%

Coherent Control of Optically Generated and Detected Picosecond Surface Acoustic Phonons

Hurley

Lewis²

2007

J. Korean Phys. Soc.

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Coherent control of electronic and phononic excitations in solids, as well as chemical and biological systems on ultrafast time scales is of current research interest. In semiconductors, coherent control of phonons has been demonstrated for acoustic and optical phonons generated in superlattice structures. The bandwidth of these approaches is typically fully utilized by employing a 1-D geometry where the laser spot size is much larger than the superlattice repeat length. In this article we demonstrate coherent control of optically generated picosecond surface acoustic phonons using sub-optical wavelength absorption gratings. The generation and detection characteristics of two material systems are investigated (aluminum absorption gratings on Si and GaAs substrates). Constructive and complete destructive interference conditions are demonstrated using two pump pulses derived from a single Michelson interferometer.

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supporting

confidence: 51%

Coherent Control of Optically Generated and Detected Picosecond Surface Acoustic Phonons

Hurley

Lewis²

2007

J. Korean Phys. Soc.

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“…where a complete structural phase transition results, is fundamentally different to those found in highly excited materials where no phase transition results, such as charge transfer compounds 40 , organic solids 41,42 or bismuth. In these cases, photoexcitation increases the dephasing rate and softens the phonon modes, but does not result in an underlying change in the symmetry of the lattice potential on an ultrafast timescale [43][44][45] . VO 2 , on the other hand, shows a distinct change in the number of phonon modes when excited above threshold, demonstrating that the laser pulse has changed the lattice potential symmetry.…”

Section: Discussionmentioning

confidence: 99%

Tracking the evolution of electronic and structural properties of VO2during the ultrafast photoinduced insulator-metal transition

et al. 2013

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We present a detailed study of the photoinduced insulator-metal transition in VO2 with broadband time-resolved reflection spectroscopy. This allows us to separate the response of the lattice vibrations from the electronic dynamics and observe their individual evolution. When exciting well above the photoinduced phase transition threshold, we find that the restoring forces that describe the ground state monoclinic structure are lost during the excitation process, suggesting that an ultrafast change in lattice potential drives the structural transition. However, by performing a series of pump-probe measurements during the non-equilibrium transition, we observe that the electronic properties of the material evolve on a different, slower, timescale. This separation of timescales suggests that the early state of VO2, immediately after photoexcitation, is a non-equilibrium state that is not well defined by either the insulating or metallic phase.

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“…Therefore, to verify that the symmetry change occurs during the excitation process, we perform a pump-probe experiment on the excited state of the system below and above the phase transition threshold. Such a technique has been previously used to demonstrate the effects of damping of soft modes [25][26][27] . Figure 4 shows the results at a probe wavelength of 525 nm.…”

Section: Phonons During the Photoinduced Phase Transition In Vomentioning

confidence: 99%

Ultrafast changes in lattice symmetry probed by coherent phonons

et al. 2012

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The electronic and structural properties of a material are strongly determined by its symmetry. Changing the symmetry via a photoinduced phase transition offers new ways to manipulate material properties on ultrafast timescales. However, to identify when and how fast these phase transitions occur, methods that can probe the symmetry change in the time domain are required. Here we show that a time-dependent change in the coherent phonon spectrum can probe a change in symmetry of the lattice potential, thus providing an all-optical probe of structural transitions. We examine the photoinduced structural phase transition in Vo 2 and show that, above the phase transition threshold, photoexcitation completely changes the lattice potential on an ultrafast timescale. The loss of the equilibrium-phase phonon modes occurs promptly, indicating a non-thermal pathway for the photoinduced phase transition, where a strong perturbation to the lattice potential changes its symmetry before ionic rearrangement has occurred.

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Optical control of coherent optical phonons in bismuth films

Cited by 208 publications

References 0 publications

Coherent Control of Optically Generated and Detected Picosecond Surface Acoustic Phonons

Coherent Control of Optically Generated and Detected Picosecond Surface Acoustic Phonons

Tracking the evolution of electronic and structural properties of VO2during the ultrafast photoinduced insulator-metal transition

Ultrafast changes in lattice symmetry probed by coherent phonons

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