Asymptotic approximations for Bloch waves and topological mode steering in a planar array of Neumann scatterers

Wiltshaw, Richard; Makwana, Mehul P.

doi:10.1016/j.wavemoti.2020.102662

Cited by 12 publications

(9 citation statements)

References 35 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…A fascinating chiral beaming phenomenon has been observed for classical and electronic valley-Hall systems [27,76]. By exciting a valley-Hall crystal near the periphery of the topological band gap (Fig.…”

Section: B Elastic Edge Waves To Chirality-locked Beam Splittingmentioning

confidence: 97%

See 1 more Smart Citation

Localizing Elastic Edge Waves via the Topological Rainbow Effect

2021

Self Cite

View full text Add to dashboard Cite

We combine two different fields, topological physics and graded metamaterials to design a topological metasurface to control and redirect elastic waves. We strategically design a two-dimensional crystalline perforated elastic plate, using a square lattice, that hosts symmetry-induced topological edge states. By concurrently allowing the elastic substrate to spatially vary in depth, we are able to convert the incident slow wave into a series of robust modes, with differing envelope modulations. This adiabatic transition localises the incoming energy into a concentrated region where it can then be damped or extracted. For larger transitions, different behaviour is observed; the incoming energy propagates along the interface before being partitioned into two disparate chiral beams. This "topological rainbow" effect leverages two main concepts, namely the quantum valley-Hall effect and the rainbow effect usually associated with electromagnetic metamaterials. The topological rainbow effect transcends specific physical systems, hence, the phenomena we describe can be transposed to other wave physics. Due to the directional tunability of the elastic energy by geometry our results have far-reaching implications for applications such as switches, filters and energy-harvesters.

show abstract

Section: B Elastic Edge Waves To Chirality-locked Beam Splittingmentioning

confidence: 97%

“…The excitation of the separated pseudospin states stems from the gradient direction of the isofrequency contours shown in Fig. 10(c) [27,76].…”

Section: B Elastic Edge Waves To Chirality-locked Beam Splittingmentioning

confidence: 99%

Localizing Elastic Edge Waves via the Topological Rainbow Effect

2021

Self Cite

View full text Add to dashboard Cite

show abstract

“…Throughout the topological literature, numerous examples of two-way beam splitters have been shown [15,[27][28][29][30][31][32][33][34][35][36][37][38][39][40][41][42] that leverage the geometry of graphenelike hexagonal structures. The restriction to two-way energy splitting is due to a conservation of a topological charge near the KK valleys and is inherent within graphenelike structures; to obtain these three-way energy splitters, square or rectangular structures must be used and not the graphenelike structures that are readily found in the topological community [16,[19][20][21][22][23][24][25][26].…”

Section: B Three-way Beam Splitting For Topological Acoustic Modesmentioning

confidence: 99%

“…Exciting progress is being made in the field of valleytronics [16,[19][20][21][22][23][24][25][26] and this whole area of research shows much promise. However, throughout the topological literature, there is a gap in experimentally showing how to split energy, over a broadband range of frequencies (about 0.5 MHz), in three directions.…”

Section: Introductionmentioning

confidence: 99%

Acoustic Topological Circuitry in Square and Rectangular Phononic Crystals

et al. 2021

Self Cite

View full text Add to dashboard Cite

We use square and rectangular phononic crystals to create experimental realizations of complex topological phononic circuits. The exotic topological transport observed is wholly reliant upon the underlying structure that must belong to either a square or rectangular lattice system and not to any hexagonal-based structure. The phononic system we use consists of a periodic array of square steel bars that partitions acoustic waves in water over a broadband range of frequencies (about 0.5 MHz). An ultrasonic transducer launches an acoustic pulse that propagates along a domain wall, before encountering a nodal point, from which the acoustic signal partitions towards three exit ports. Numerical simulations are performed to clearly illustrate the highly resolved edge states as well as corroborate our experimental findings. To achieve complete control over the flow of energy, we need to create power division and redirection devices. The tunability afforded by our designs, in conjunction with the topological robustness of the modes, will lead to incorporation into acoustical devices.

show abstract

“…Exciting progress is being made in the field of valleytronics [14,[16][17][18][19][20][21][22][23] and this whole area of research shows much promise. However throughout all of the topological literature there is a gap in experimentally showing how to split energy, over a broadband range of frequencies, in three-directions.…”

Section: Introductionmentioning

confidence: 99%

Acoustic topological circuitry in square and rectangular phononic crystals

Laforge¹,

Wiltshaw²,

Laude³

et al. 2020

Preprint

Self Cite

View full text Add to dashboard Cite

We systematically engineer a series of square and rectangular phononic crystals to create experimental realisations of complex topological phononic circuits. The exotic topological transport observed is wholly reliant upon the underlying structure which must belong to either a square or rectangular lattice system and not to any hexagonal-based structure. The phononic system chosen consists of a periodic array of square steel bars which partitions acoustic waves in water over a broadband range of frequencies (∼ 0.5 MHz). An ultrasonic transducer launches an acoustic pulse which propagates along a domain wall, before encountering a nodal point, from which the acoustic signal partitions towards three exit ports. Numerical simulations are performed to clearly illustrate the highly resolved edge states as well as corroborate our experimental findings. To achieve complete control over the flow of energy, power division and redirection devices are required. The tunability afforded by our designs, in conjunction with the topological robustness of the modes, will result in their assimilation into acoustical devices.

show abstract

Asymptotic approximations for Bloch waves and topological mode steering in a planar array of Neumann scatterers

Cited by 12 publications

References 35 publications

Localizing Elastic Edge Waves via the Topological Rainbow Effect

Localizing Elastic Edge Waves via the Topological Rainbow Effect

Acoustic Topological Circuitry in Square and Rectangular Phononic Crystals

Acoustic topological circuitry in square and rectangular phononic crystals

Contact Info

Product

Resources

About