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Complexity of modes. (a) Displacement fields of four first observable Lamb modes as calculated by FEM, with quasi-symmetric (qS n ) and quasiantisymmetric (qA n ) ones. Color scale: green -low, yellow -medium, redlarge. (b-e) Overlayed Stokes and anti-Stokes branches of BLS spectra for different configurations of pump and probe (see notes in each panel). Solid lines are experimental data fits. (f) Experimental (colored map) and calculated (lines) thermal phonon dispersion of the studied sample. Red-line branches are active in the pumped-BLS experiment. The dashed horizontal line depicts a range of measured wavenumbers due to the probing objective lens NA.
Source publication
Observation of Fano resonances in various physical phenomena is usually ascribed to the coupling of discrete states with background continuum, as it has already been reported for various physical phenomena. Here, we report on Fano lineshapes of nonthermal GHz phonons generated and observed with pumped Brillouin light scattering in gold-silicon thin...
Contexts in source publication
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... situation described above gets more complex for higher order Lamb modes and with varying the configuration of pump and probe. Fig. 3 gathers pumped-BLS spectra recorded for all four possible experimental geometries at the spectral range extended to 68 GHz. The observed peaks were identified based on the measured (thermal phonons) and calculated (finite element method, FEM) dispersion relations plotted in Fig. 3f, as well as their calculated displacement fields (Fig. ...
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... Lamb modes and with varying the configuration of pump and probe. Fig. 3 gathers pumped-BLS spectra recorded for all four possible experimental geometries at the spectral range extended to 68 GHz. The observed peaks were identified based on the measured (thermal phonons) and calculated (finite element method, FEM) dispersion relations plotted in Fig. 3f, as well as their calculated displacement fields (Fig. ...
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... probe. Fig. 3 gathers pumped-BLS spectra recorded for all four possible experimental geometries at the spectral range extended to 68 GHz. The observed peaks were identified based on the measured (thermal phonons) and calculated (finite element method, FEM) dispersion relations plotted in Fig. 3f, as well as their calculated displacement fields (Fig. ...
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... Fano lineshape spans over all peaks on the broader frequency range, and its extent varies with three different factors: Stokes/antiStokes side of the spectrum, frequency, and pump/probe configuration, evident in spectra presented in Fig. 3b-e. Note that Stokes parts of the spectra were mirrored horizontally for convenient comparison. Fitting of spectra by a sum of Fano peaks interfering with a background (see Supplementary Materials for details) proves that this variability is caused by the q factor, which can be attributed to the difference in the initial phase of the ...
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... heterojunction, the fs laser excitation offers an unprecedented 8000-fold enhancement of the BLS signal (Fig. 2), with the previous record being a 300-fold enhancement for pure Si. Moreover, the symmetry lowering of AuSi MBs, compared to pure Si, enables the detection of multiple Lamb modes with both symmetric and antisymmetric character (Fig. 3). Moreover, we observed high variability of the coupling parameter depending on the pump and probe geometrical configuration, mode frequency and Stokes/antiStokes side of the spectrum. These findings prove that pumped BLS has strong potential for the characterization of phononic metamaterials, such as phononic crystals and topological ...
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... situation described above gets more complex for higher order Lamb modes and with varying the configuration of pump and probe. Fig. 3 gathers pumped-BLS spectra recorded for all four possible experimental geometries at the spectral range extended to 68 GHz. The observed peaks were identified based on the measured (thermal phonons) and calculated (finite element method, FEM) dispersion relations plotted in Fig. 3f, as well as their calculated displacement fields (Fig. ...
Context 7
... Lamb modes and with varying the configuration of pump and probe. Fig. 3 gathers pumped-BLS spectra recorded for all four possible experimental geometries at the spectral range extended to 68 GHz. The observed peaks were identified based on the measured (thermal phonons) and calculated (finite element method, FEM) dispersion relations plotted in Fig. 3f, as well as their calculated displacement fields (Fig. ...
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... probe. Fig. 3 gathers pumped-BLS spectra recorded for all four possible experimental geometries at the spectral range extended to 68 GHz. The observed peaks were identified based on the measured (thermal phonons) and calculated (finite element method, FEM) dispersion relations plotted in Fig. 3f, as well as their calculated displacement fields (Fig. ...
Context 9
... Fano lineshape spans over all peaks on the broader frequency range, and its extent varies with three different factors: Stokes/antiStokes side of the spectrum, frequency, and pump/probe configuration, evident in spectra presented in Fig. 3b-e. Note that Stokes parts of the spectra were mirrored horizontally for convenient comparison. Fitting of spectra by a sum of Fano peaks interfering with a background (see Supplementary Materials for details) proves that this variability is caused by the q factor, which can be attributed to the difference in the initial phase of the ...
Context 10
... heterojunction, the fs laser excitation offers an unprecedented 8000-fold enhancement of the BLS signal (Fig. 2), with the previous record being a 300-fold enhancement for pure Si. Moreover, the symmetry lowering of AuSi MBs, compared to pure Si, enables the detection of multiple Lamb modes with both symmetric and antisymmetric character (Fig. 3). Moreover, we observed high variability of the coupling parameter depending on the pump and probe geometrical configuration, mode frequency and Stokes/antiStokes side of the spectrum. These findings prove that pumped BLS has strong potential for the characterization of phononic metamaterials, such as phononic crystals and topological ...
Citations
... An interesting intermediate situation is presented in the article [4], in which case a continuous laser is used to detect the interaction with coherent phonons optically generated by ultrashort pump optical pulses. The detected signals are then 3-4 orders of magnitude higher than those detected when there is no pump, i.e., when only spontaneous thermal phonons are detected. ...
Characterization of lattice properties of monocrystalline semiconductors (MS) has been rapidly advanced. Of particular interest is the use of shear strains induced by optoacoustic-bulk-waves. However, this technique has been hindered owing to the lack of quantitative correlations between optoacoustic-bulk-waves-induced shear strains and anisotropic photoelasticity of MS. Motivated by this, a multiphysics model is developed to interrogate the coupling phenomena and interaction between optical polarization and shear strains in MS. With the model, perturbation to the polarization of a monochromatic laser beam, upon interacting with optoacoustic waves in MS, is scrutinized quantitatively. Experimental results are in agreement with those from the model, both revealing the polarization perturbed by shear strains quantitatively depends on the crystal orientation and crystal-structure-related symmetry, which are jointly governed by mechanical/photoelastic/optical anisotropies of MS. The approach has paved a new way for selectively acquiring high-sensitivity shear components of optoacoustic-ultrasonic-waves for in situ, high-definition characterization of anisotropic MS.
