Fundamentals of the grating-assisted surface acoustic wave-plate bulk acoustic wave interaction
2008 (English)In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 104, no 3, 034111- p.Article in journal (Refereed) Published
The resonant interaction between Rayleigh surface acoustic waves (SAWs) and Lamb modes in a plate [in general, plate bulk acoustic waves (plate BAW)] through the loading effect of an infinite periodical grating defined on the plate surface is theoretically described and its fundamental characteristics revealed. Further, the eigenmodes along with amplitude ratios inside such types of gratings are determined. Analytical expressions describing the interaction have also been derived. The analysis performed in here represents the first fundamental description of the problem. In this work, only the case of isotropic elastic medium is considered, thus illuminating the fundamentals of the interaction itself, excluding the effects of crystal anisotropy. The modes' dispersion is found to exhibit a complex stopband structure. In the vicinity of the resonance condition the interaction of the waves generates new three-component eigenmodes. Specifically, two independent eigenmodes have been found to coexist in the structure due to the presence of the coupler, i.e., the periodic grating. One of them is represented by two contrapropagating SAWs coupled to a plate BAW, while the other one is represented by a near-onset Lamb mode generating two contrapropagating SAWs. Three general cases of the interaction representing Lamb modes with cutoff frequencies equal, smaller, and grater than the second Bragg frequency of the grating are considered, respectively. Analogies can be found with other interwave interactions as, for example, between light and optical phonons in solids.
Place, publisher, year, edition, pages
2008. Vol. 104, no 3, 034111- p.
Engineering and Technology
IdentifiersURN: urn:nbn:se:uu:diva-109126DOI: 10.1063/1.2965194ISI: 000258493900120OAI: oai:DiVA.org:uu-109126DiVA: diva2:248929