ISSN:
1432-0630
Schlagwort(e):
68.25
;
42.80Lt
;
78.35
;
43.30
Quelle:
Springer Online Journal Archives 1860-2000
Thema:
Maschinenbau
,
Physik
Notizen:
Abstract The propagation of surface acoustic waves at microwave frequencies (∼1010 Hz) was studied on proton exchanged LiNbO3 crystals by means of Brillouin scattering. The proton exchange causes a large velocity reduction for surface acoustic waves propagating in the x−y plane of ay-cut crystal as well as for longitudinal bulk acoustic waves travelling in the proton exchanged sub-surface region. The velocity reduction amounts to about 20% for both types of waves. The corresponding elastic constants are reduced even by about 40% since the density remains almost constant. This softening seems to involve both the shear and compressional elastic constants, but in an anisotropic way. Thus by proton exchange it is possible to build acoustic waveguides adjacent to the surface, similar to the construction of optical waveguides. By a lateral control of the proton exchange rate optical elements for ultrasonic waves, for example, acoustic lenses can be produced without deformation of the flat surface. The absorption of surface acoustic waves on proton exchanged surfaces is stronger than on pure LiNbO3 indicating a novel absorption mechanism becoming active in the proton exchanged material.
Materialart:
Digitale Medien
URL:
http://dx.doi.org/10.1007/BF00616062
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