Table 1. The measured Brillouin frequency shifts, hypersonic velocities, linewidths (FWHM), attenuation coefficient, phonon mean free paths, and intensity at longitudinal and shear phonons. The intensity means the number of photons in FWHM of one Brillouin peak.
| Polarization | Brillouin Shift (GHz) | Hypersonic Velocity (km/s) |
Linewidth (GHz) |
Attenuation (μm−1) |
Phonon Mean Free Path (μm) | Intensity (photons/s) | |
|---|---|---|---|---|---|---|---|
| Polycarbonate | VV | 11.68 | 2.43 | 0.36 | 0.47 | 1.07 | 2.2 × 104 |
| VH | 5.16 | 1.08 | 0.68 | 1.97 | 0.25 | 1.2 × 103 | |
| Fused Quartz |
VV | 26.03 | 5.91 | 0.18 | 0.10 | 5.24 | 7.1 × 102 |
| VH | 15.90 | 3.63 | 0.57 | 0.49 | 1.01 | 1.4 × 102 | |
| Borosilicate Glass |
VV | 24.47 | 5.50 | 0.11 | 0.06 | 7.96 | 1.1 × 103 |
| VH | 14.73 | 3.32 | 0.68 | 0.65 | 0.77 | 1.0 × 102 | |