Imaging Ripples on Phononic Crystals Reveals Acoustic Band Structure and Bloch Harmonics

Profunser, Dieter M.; Wright, Oliver B.; Matsuda, Osamu

doi:10.1103/physrevlett.97.055502

Cited by 82 publications

(40 citation statements)

References 27 publications

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“…(For a more detailed description, see the Supplementary Information.) Recently, this method has been applied to the investigation of phononic crystals 20 . By recovering the wavevectors as a function of time, we can investigate the dynamics of the individual eigenstates.…”

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confidence: 99%

Ultrafast evolution of photonic eigenstates in k-space

et al. 2007

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Periodic structures have a large influence on propagating waves. This holds for various types of waves over a large range of length scales: from electrons in atomic crystals 1 and light in photonic crystals 2-4 to acoustic waves in sonic crystals 5 . The eigenstates of these waves are best described with a band structure, which represents the relation between the energy and the wavevector (k). This relation is usually not straightforward: owing to the imposed periodicity, bands are folded into every Brillouin zone, inducing splitting of bands and the appearance of bandgaps. As a result, exciting phenomena such as negative refraction 6,7 , autocollimation of waves 8,9 and low group velocities 10-12 arise. k-space investigations of electronic eigenstates have already yielded new insights into the behaviour of electrons at surfaces and in novel materials [13][14][15][16] . However, for a complete characterization of a structure, an understanding of the mutual coupling of eigenstates is also essential. Here, we investigate the propagation of light pulses through a photonic crystal structure using a near-field microscope 17,18 . Tracking the evolution of the photonic eigenstates in both k-space and time allows us to identify individual eigenstates and to uncover their dynamics and coupling to other eigenstates on femtosecond timescales even when co-localized in real space and time.

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confidence: 99%

Ultrafast evolution of photonic eigenstates in k-space

et al. 2007

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“…Instead of a single-point measurement, the sample may also be scanned to obtain two-dimensional images of wave propagation [60,61]. The technique has recently also been applied to study wave interaction with phononic crystal samples [62][63][64][65].…”

Section: Optical Characterization Of Surface Vibrationsmentioning

confidence: 99%

“…This line scan method has been used together with angular spectrum theory to characterize both the slowness and wave attenuation [15]. On the other hand, time-domain optical pump-probe characterization has been used for spot excitation of waves and observation of the resulting ripples on the crystal surface [63]. It has been demonstrated that a few acoustic wave lengths away from the source, the phase front follows the shape of the surface wave, i.e., the locus of the group velocity as a function of the propagation angle.…”

Section: Wave Slowness From Random Saw Fieldsmentioning

confidence: 99%

Measurement of evanescent wave properties of a bulk acoustic wave resonator [Letters]

Kokkonen

Meltaus

Pensala

et al. 2012

IEEE Trans. Ultrason., Ferroelect., Freq. Contr.

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Aalto University publication series DOCTORAL DISSERTATIONS 112/2014 © Kimmo Kokkonen AbstractThe research summarized in this dissertation focuses on the development of a heterodyne scanning laser interferometer and of data-analysis techniques for the characterization and analysis of the surface vibration fields in microacoustic devices and test structures.The heterodyne laser interferometer enables a phase-sensitive, absolute-amplitude detection of the out-of-plane component of a surface vibration field, with a minimum detectable amplitude of less than a picometer, while the lateral resolution is better than 1 micrometer. The instrument features a flat frequency response up to 6 GHz.The phase-sensitive absolute-amplitude data enables the visualization of the actual wave behavior in electromechanical components and test structures, but more importantly, it is the basis for further analysis. The research instrument is applied to the study of electroacoustic devices based on surface acoustic wave (SAW) and bulk acoustic wave (BAW) technologies. Two novel SAW devices are studied in detail: a phononic crystal (PnC) structure and a scattering structure resulting in a random wave field. PnCs are acoustic metamaterials that can provide engineered material properties. The laser interferometric measurements were amongst the first to directly characterize the wave interaction with the PnC. SAW slowness curves of an anisotropic substrate material are extracted by measuring and analyzing the scattered random wave field. Data analysis methods are developed further in the context of BAW research by experimentally addressing two important aspects of device design: the correct operation of the acoustic reflector used to confine the energy in the resonator, and investigation of the role of the dispersion and standing wave resonances to the spurious responses often observed in high-Q resonators. Fourier transform techniques are used for selective visualization of wave fields and for the extraction of the dispersion characteristics of the plate-waves. The dispersion data are then further used to analyze the transfer characteristics of an acoustic reflector and to study the properties of lateral eigenresonances and the lateral energy confinement in detail.The research described in this thesis provides a detailed characterization of the operation of SAW and BAW devices and effects within, highlighting and further developing the experimental characterization capabilities and data-analysis methods.Keywords laser interferometry, microacoustics, surface acoustic waves, bulk acoustic waves Tiivistelmä Väitöskirjatyö käsittelee heterodyne-tyyppisen laserinterferometrin sekä interferometrin tuottaman datan analyysitekniikoiden kehittämistä pintavärähtelykenttien karakterisoimiseksi ja analysoimiseksi mikroakustisissa komponenteissa ja testirakenteissa.Työssä rakennettu heterodynelaserinterferometri mahdollistaa pintavärähtelyiden vaiheherkät absoluuttiamplitudimittaukset aina 6 GHz taajuuteen asti. Laitteisto kykenee värähtely-kenttien k...

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“…It has been used to investigate the dispersion relation of surface acoustic modes [42], acoustic band structure [43] and to observe the diffraction angles [44]. In infinite space and time domains, the FT is written as…”

Section: A Diffraction Effect -Spatial Filteringmentioning

confidence: 99%

Phononic thermal resistance due to a finite periodic array of nano-scatterers

Nghiem

Chapuis

2016

Journal of Applied Physics

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The wave property of phonons is employed to explore the thermal transport across a finite periodic array of nano-scatterers such as circular and triangular holes. As thermal phonons are generated in all directions, we study their transmission through a single array for both normal and oblique incidences, using a linear dispersionless time-dependent acoustic frame in a two-dimensional system. Roughness effects can be directly considered within the computations without relying on approximate analytical formulae. Analysis by spatio-temporal Fourier transform allows us to observe the diffraction effects and the conversion of polarization. Frequency-dependent energy transmission coefficients are computed for symmetric and asymmetric objects. We demonstrate that the phononic array acts as an efficient thermal barrier by applying the theory of thermal boundary (Kapitza) resistances to arrays of smooth scattering holes in silicon for an exemplifying periodicity of 10 nm in the [5-100 K] temperature range. It is observed that the associated thermal conductance has the same temperature dependence than that without phononic filtering.

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Imaging Ripples on Phononic Crystals Reveals Acoustic Band Structure and Bloch Harmonics

Cited by 82 publications

References 27 publications

Ultrafast evolution of photonic eigenstates in k-space

Ultrafast evolution of photonic eigenstates in k-space

Measurement of evanescent wave properties of a bulk acoustic wave resonator [Letters]

Phononic thermal resistance due to a finite periodic array of nano-scatterers

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