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dc.contributor.supervisor Page, John (Physics and Astronomy) en
dc.contributor.author Sukhovich, Alexey
dc.date.accessioned 2007-09-14T17:25:51Z
dc.date.available 2007-09-14T17:25:51Z
dc.date.issued 2007-09-14T17:25:51Z
dc.identifier.uri http://hdl.handle.net/1993/2828
dc.description.abstract Novel wave phenomena in two- and three-dimensional (2D and 3D) phononic crystals were investigated experimentally using ultrasonic techniques. Resonant tunneling of ultrasonic waves was successfully observed for the first time by measuring the transmission of ultrasound pulses through a double barrier consisting of two 3D phononic crystals separated by a cavity. This effect is the classical analogue of resonant tunneling of a quantum mechanical particle through a double potential barrier, in which transmission reaches unity at resonant frequencies. For phononic crystals, the tunneling peak was found to be less than unity, an effect that was explained by absorption. The dynamics of resonant tunneling was explored by measuring the group velocities of the ultrasonic pulses. Very slow and very fast velocities were found at frequencies close to and at the resonance, respectively. These extreme values are less than the speed of sound in air and greater than the speed of sound in any of the crystal’s constituent materials. Negative refraction and focusing effects in 2D phononic crystals were also observed. Negative refraction of ultrasound was demonstrated unambiguously in a prism-shaped 2D crystal at frequencies in the 2nd pass band where the wave vector and group velocity are opposite. The Multiple Scattering Theory and Snell’s law allowed theoretical predictions of the refraction angles. Excellent agreement was found between theory and experiment. The negative refraction experiments revealed a mechanism that can be used to focus ultrasound using a flat phononic crystal, and experiments to demonstrate the focusing of ultrasound emitted by several point sources were successfully carried out. The importance of using phononic crystals with circular equifrequency contours, as well as matching the size of the contours inside and outside the crystal, was established. Both conditions were satisfied by a flat phononic crystal of steel rods, in which the liquid inside the crystal (methanol) was different from the outside medium (water). The possibility of achieving subwavelength resolution using this phononic crystal was investigated with a subwavelength line source (a miniature strip-shaped transducer, approximately lambda/5 wide, where lambda is sound wavelength in water). A resolution of 0.55lambda was found, which is just above the diffraction limit lambda/2. en
dc.format.extent 3770317 bytes
dc.format.mimetype application/pdf
dc.language.iso en_US
dc.rights info:eu-repo/semantics/openAccess
dc.subject waves en
dc.subject phononic crystals en
dc.subject negative refraction en
dc.subject imaging en
dc.subject subwavelength resolution en
dc.title Wave phenomena in phononic crystals en
dc.type info:eu-repo/semantics/doctoralThesis
dc.degree.discipline Physics and Astronomy en
dc.contributor.examiningcommittee Deymier, Pierre (University of Arizona) Southern, Byron (Physics and Astronomy) van Lierop, Johan (Physics and Astronomy) Oliver, Derek (Electrical and Computer Engineering) en
dc.degree.level Doctor of Philosophy (Ph.D.) en
dc.description.note October 2007 en


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