Wide Band Gap Phononic Crystals Abstract: Controlling the flow of phonons can lead to many interesting applications and basic scientific dscoveries. Integrated management of acoustic, heat and electromagnetic waves may have significant impact on novel devices employing phonon-photon interactions. Some of the potential applications include thermal management, compact wireless and sensing devices and phasers. In this project we design, fabricate and test phononic bandgap structures. We employ Brillouin light scattering in our measurements typically at GHz phononic ranges.
Keywords: Phononic Crystals
Collaborators: Zhandos Utegulov (Idaho National Laboratory), Maria Kafesaki (University of Crete, Greece), Eleftherios N. Economou (University of Crete, Greece), Costas Soukoulis (Ames Laboratory), Thomas Koschny (Ames Laboratory), Tansel Karabacak (University of Arkansas, Little Rock).
Controlling the flow of phonons has interesting basic science and important applications, such as heat management, reduction of noise in electronic circuits, tunable filters, enhanced acousto-optical interactions [1-2], compact wireless and sensing devices [3]. Driven by its developing fundamental theory and other proposed novel applications (such as sound shields, acoustic superlenses, acoustic lasers) phononic crystal research continues to attract a growing attention [2]. Much of the work, however, has been restricted to sonic and ultrasonic phononic crystals mainly due to the experimental convenience and promising applications of remote sensing and medical diagnostics. It is challenging to fabricate and characterize hypersonic phononic crystals, despite entirely new phenomena observed at such scales [1]. First, controlling the phononic density of states affects the thermal conductivity and heat capacity. Second, it is possible to overlap phononic and photonic bandgaps leading to enhanced acousto-optical interactions, which has implications ranging from optical cooling and shock-wave mediated light frequency shift to other acousto-optical devices.
Gorishnyy, et al [1] has provided foundations for experimental studies of hypersonic phononic crystals by employing Brillouin light scattering to directly measure the phononic band structure. Cheng, et al [2] reported the first observation of a hypersonic bandgap in face-centered-cubic colloidal crystals formed by self-assembly of polystyrene nanoparticles with subsequent fluid infiltration.
Moldavan and Thomas demonstrated theoretically simultaneous localization of photons and phonons in the same spatial region of two-dimensional periodic array of dielectric/elastic material which exhibit band gaps for both electromagnetic and elastic waves [4]. Overlapping the phononic and photonic band gap may lead to interesting acousto-optical devices due to the strong influence on photon-phonon interactions as well as integrated management of sound, heat and light propagation. Mohammedi et al recently showed the evidence of large complete phononic bandgaps in silicon phononic crystal slabs.
For a good overview of phononic crystals and potential applications see the presentation (Photonic and Phononic Crystal Research at Sandia) by Sandia Natioanal Laboratories.
In this project we explore both theoretically and experimentally the underlying principles for wide bandgap phononic crystals. We design, fabricate and test the proposed structures. We use Brillouin light scattering for measurement at GHz ranges. Our collaborators include Zhandos Utegulov (University of Nebraska, Lincoln), Maria Kafesaki (University of Crete, Greece), Eleftherios N. Economou (University of Crete, Greece), Tansel Karabacak (University of Arkansas, Little Rock), Che Ting Chan (Hong Kong University of Science and Technology).
References
[1] T. Gorishnyy, C. K. Ullal, M. Maldovan, G. Fytas, and E. L. Thomas, Hypersonic phononic crystals, Phys. Rev. Lett. 94, 115501 (2005).
[2] W. Cheng, J. Wang, J. Jonas, G. Fytas, and N. Stefanou, Observation and tuning of hypersonic bandgaps in colloidal crystals, Nature Materials 5, 830 (2006).
[3] S. Mohammedi, A. A. Eftekhar, A. Khelif, W. D. Hunt, adn A. Adibi, Evidence of large high frequency complete phononic band gaps in silicon phononic crystal plates, Appl. Phys. Lett. 92, 221905 (2008).
[4] M. Moldavan and E. L. Thomas, Simultaneous localization of photons and phonons in two-dimensional periodic structures, Appl. Phys. Lett. 88, 251907 (2006).