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Phononics – A field that has come of age
Ultrasonics 54 (2014) 1
Contents lists available at ScienceDirect
Ultrasonics journal homepage: www.elsevier.com/locate/ultras
Phononics – A field that has come of age
Phononics is a relatively young field that has seen an almost exponential growth in publications in recent years. With the successful conclusion of Phononics 2013, the 2nd International Conference on Phononic Crystals/Metamaterials, Phonon Transport and Optomechanics, which took place in Sharm El-Sheikh, Egypt, June 2–7, 2013 (Conference website www.phononics2013.org), the field can now be said to have come of age. The term phononics is a synonym for phononic crystals and metamaterials used in its broadest sense. It centers on the study of acoustic and elastic waves in structured materials, usually periodic in one, two or three dimensions. Wave propagation in periodic structures is a subject that goes back to the work of William Rowan Hamilton, John Baden-Powell and Lord Rayleigh in the 19th century. For much of the 20th century it was devoted mainly to electrons, phonons and various diffraction phenomena in crystalline solids. What distinguishes phononic crystals/metamaterials from natural crystals is that they are engineered structured materials, rather than thermodynamically grown periodic arrangements of atoms or molecules. As such, they tend to have larger spatial periods than natural crystals, although with modern nanofabrication techniques, the smallest phononic crystal/metamaterial lattice constants are comparable to the lattice constants of natural crystals with very large bases. Likewise the frequency spectra of some phononic crystals/metamaterials are in the range of phonon spectra. The term phononics has been adapted from photonics, an extremely active field for some decades. Indeed, there is an overlap between these two fields now, which goes by the name of phoxonic crystals, i.e. bandgap materials which support both acoustic and electromagnetic waves, and bring about coupling between the two. There are numerous analogues of effects and problems being addressed in phononics and photonics, and also issues which are perhaps more specific to the elastic waves of phononics. Current topics in phononics that are attracting considerable attention include acoustic isolation through the use of metamaterials with embedded resonant elements or periodic structures designed to have suitable band gaps, acoustic cloaking, acoustic and thermal diodes, guided waves in periodically structured surfaces and interfaces and plates, and in lower dimensional structures such as graphene and nanowires and nanotubes, negative refraction
0041-624X/$ - see front matter Ó 2013 Published by Elsevier B.V. http://dx.doi.org/10.1016/j.ultras.2013.08.014
and superlensing, engineering thermal transport in nanostructures, phoxonic crystals that exhibit dual phononic/photonic band gaps, dissipative waves, nonlinear waves, enhancing sound in chirped sonic crystals and the quantum dot single phonon detector. Phononics 2013 provided an excellent window on the current state of this evolving field of research. An extraordinarily large proportion of the founders and current leaders of the field attended and presented plenary and invited papers and colloquia. It is a tribute to the organizers of the conference, Ihab El-Kady of Sandia National Laboratories and Mahmoud Hussein of the University of Colorado Boulder, that they were able to attract to the conference so many of the luminaries of the field. What they provided was an excellently run conference of the highest scientific standard. All talks were sequential with no parallel sessions, so it was possible to gain a comprehensive overview of the field by attending. Two prizes were awarded at Phononics 2013. The 2013 Bloch Prize went to Professor Bahram Djfari-Rouhani for his contributions to ‘‘superlattices, phononic crystals, phonon-photon interactions, plasmonics and other related areas’’. The 2013 Brillouin Medal was awarded to Professors Ping Sheng, Che Ting Chan and Zhiyu Yang for their discovery of the concept of a ‘‘locally resonant acoustic metamaterial’’. Phononics is a young and evolving field with no rigid boundaries, and that is expanding into new domains such as phonon transport and optomechanics. The main thread holding these different activities together is, and will probably remain, phononic crystals/metamaterials and the role they can play in a wide range of physical effects and technological applications. The next two Phononics 20xx conferences in the planning stage are in Paris, France in June 2015, organized by Bernard Bonello, Abdelkrim Khelif and Bahram Djafari-Rouhani and in Changsha, China in June 2017, organized by Jihong Wen, Li Boawen and Ping Sheng. The International Phononics Society (IPS) has recently been established to promote the advance of the field in various ways, and oversee the organization of the biennial Phononics 20xx conferences. Its official webpage is www.phononics.org. Mahmoud Hussein is thanked for helpful comments on this editorial. A.G. Every
Contents lists available at ScienceDirect
Ultrasonics journal homepage: www.elsevier.com/locate/ultras
Phononics – A field that has come of age
Phononics is a relatively young field that has seen an almost exponential growth in publications in recent years. With the successful conclusion of Phononics 2013, the 2nd International Conference on Phononic Crystals/Metamaterials, Phonon Transport and Optomechanics, which took place in Sharm El-Sheikh, Egypt, June 2–7, 2013 (Conference website www.phononics2013.org), the field can now be said to have come of age. The term phononics is a synonym for phononic crystals and metamaterials used in its broadest sense. It centers on the study of acoustic and elastic waves in structured materials, usually periodic in one, two or three dimensions. Wave propagation in periodic structures is a subject that goes back to the work of William Rowan Hamilton, John Baden-Powell and Lord Rayleigh in the 19th century. For much of the 20th century it was devoted mainly to electrons, phonons and various diffraction phenomena in crystalline solids. What distinguishes phononic crystals/metamaterials from natural crystals is that they are engineered structured materials, rather than thermodynamically grown periodic arrangements of atoms or molecules. As such, they tend to have larger spatial periods than natural crystals, although with modern nanofabrication techniques, the smallest phononic crystal/metamaterial lattice constants are comparable to the lattice constants of natural crystals with very large bases. Likewise the frequency spectra of some phononic crystals/metamaterials are in the range of phonon spectra. The term phononics has been adapted from photonics, an extremely active field for some decades. Indeed, there is an overlap between these two fields now, which goes by the name of phoxonic crystals, i.e. bandgap materials which support both acoustic and electromagnetic waves, and bring about coupling between the two. There are numerous analogues of effects and problems being addressed in phononics and photonics, and also issues which are perhaps more specific to the elastic waves of phononics. Current topics in phononics that are attracting considerable attention include acoustic isolation through the use of metamaterials with embedded resonant elements or periodic structures designed to have suitable band gaps, acoustic cloaking, acoustic and thermal diodes, guided waves in periodically structured surfaces and interfaces and plates, and in lower dimensional structures such as graphene and nanowires and nanotubes, negative refraction
0041-624X/$ - see front matter Ó 2013 Published by Elsevier B.V. http://dx.doi.org/10.1016/j.ultras.2013.08.014
and superlensing, engineering thermal transport in nanostructures, phoxonic crystals that exhibit dual phononic/photonic band gaps, dissipative waves, nonlinear waves, enhancing sound in chirped sonic crystals and the quantum dot single phonon detector. Phononics 2013 provided an excellent window on the current state of this evolving field of research. An extraordinarily large proportion of the founders and current leaders of the field attended and presented plenary and invited papers and colloquia. It is a tribute to the organizers of the conference, Ihab El-Kady of Sandia National Laboratories and Mahmoud Hussein of the University of Colorado Boulder, that they were able to attract to the conference so many of the luminaries of the field. What they provided was an excellently run conference of the highest scientific standard. All talks were sequential with no parallel sessions, so it was possible to gain a comprehensive overview of the field by attending. Two prizes were awarded at Phononics 2013. The 2013 Bloch Prize went to Professor Bahram Djfari-Rouhani for his contributions to ‘‘superlattices, phononic crystals, phonon-photon interactions, plasmonics and other related areas’’. The 2013 Brillouin Medal was awarded to Professors Ping Sheng, Che Ting Chan and Zhiyu Yang for their discovery of the concept of a ‘‘locally resonant acoustic metamaterial’’. Phononics is a young and evolving field with no rigid boundaries, and that is expanding into new domains such as phonon transport and optomechanics. The main thread holding these different activities together is, and will probably remain, phononic crystals/metamaterials and the role they can play in a wide range of physical effects and technological applications. The next two Phononics 20xx conferences in the planning stage are in Paris, France in June 2015, organized by Bernard Bonello, Abdelkrim Khelif and Bahram Djafari-Rouhani and in Changsha, China in June 2017, organized by Jihong Wen, Li Boawen and Ping Sheng. The International Phononics Society (IPS) has recently been established to promote the advance of the field in various ways, and oversee the organization of the biennial Phononics 20xx conferences. Its official webpage is www.phononics.org. Mahmoud Hussein is thanked for helpful comments on this editorial. A.G. Every