Phononic crystal wave structures

• US 8,054,145 B2
• Filed: 04/30/2009
• Issued: 11/08/2011
• Est. Priority Date: 04/30/2008
• Status: Expired due to Fees

• Current Assignee: Georgia Tech Research Corporation (University System of Georgia)
• Original Assignee: Georgia Tech Research Corporation (University System of Georgia)
• Inventors: Eftekhar, Ali Ashgar, Mohammadi, Saeed, Adibi, Ali
• Primary Examiner(s): TAKAOKA, DEAN O
• Application Number:
  US12/433,888
• Publication Number:
  US 20090295505A1
• Time in Patent Office: 922 Days
• Field of Search: 333/186, 333/187, 333/248, 29/253.5
• US Class Current: 333/186
• CPC Class Codes: H03H 3/08 for the manufacture of resonators or networks using surface acoustic waves
• CPC Class Codes: H03H 9/02645 Waffle-iron or dot arrays
• CPC Class Codes: H03H 9/02976 with semiconductor devices
• CPC Class Codes: H10N 30/40 with electrical input and electrical output, e.g. functioning as transformers

Abstract

Phononic crystal wave structures and methods of making same are discussed in this application. According to some embodiments, an acoustic structure can generally comprise a phononic crystal slab configured as a micro/nano-acoustic wave medium. The phononic crystal slab can define an exterior surface that bounds an interior volume, and the phononic crystal slab can be sized and shaped to contain acoustic waves within the interior volume of the phononic crystal slab. The phononic crystal slab can comprise at least one defect portion. The defect portion can affect periodicity characteristics of the phononic crystal slab. The defect portion can be shaped and arranged to enable confinement and manipulation of acoustic waves through the defect portion(s) of phononic crystal slab. Other aspects, features, and embodiments are also claimed and described.

Claims

1. A micro/nano-mechanical acoustical device, the device comprising:

a phononic crystal slab configured as an micro/nano-acoustical wave medium, the phononic crystal slab defining an exterior surface that bounds an interior volume, the phononic crystal slab sized and shape to contain acoustical waves within the interior volume of the phononic crystal slab;

wherein a portion of the phononic crystal slab comprises a periodic array of empty inclusions creating a phononic band gap.

2. The device of claim 1, wherein the phononic crystal slab has a thickness ranging from less than a wavelength of the carried acoustical waves to about ten times the wavelength of the carried acoustical wave.

3. The device of claim 1, further comprising opposing end anchors respectively located at opposing ends of the phononic crystal slab to support the phononic crystal slab over a void.

4. The device of claim 1, wherein the phononic crystal slab is a sub-component of at least one of a mechanical resonator, a waveguide, a multiplexer, a demultiplexer and a filter.

5. The device of claim 1, wherein the phononic crystal slab is an unsupported silicon plate and comprises a lattice array of empty periodic inclusions.

6. The device of claim 5, wherein the lattice array of periodic inclusions includes at least one of a triangular lattice, a square lattice, a hexagonal lattice, or a polygonal lattice.

7. The device of claim 1, further comprising a first transducer and a second transducer, both proximately situated to the phononic crystal slab, the first transducer providing the acoustical waves and the second transducer receiving the acoustical waves.

8. The device of claim 1, the phononic crystal slab further comprising at least one phononic crystal plate section that comprises a multi-dimensional array of periodic inclusions.

9. The micro/nano-mechanical acoustical device of claim 1, wherein the phononic crystal slab further comprises at least one defect portion that affects periodicity characteristics of the phononic crystal slab, the defect portion being shaped and arranged to enable confinement of acoustical waves through the defect portion of phononic crystal slab.

10. The device of claim 9, wherein the defect portion is a linear defect region centrally disposed along the phononic crystal slab, the linear defect region ranging from at least one line to a plurality of lines, the linear defect region being straddled by the portion of the phononic crystal slab that comprises the periodic array of empty inclusions.

11. The device of claim 9, wherein the at least one defect portion is arranged as a two-dimensional defect region disposed at a predetermined position along the phononic crystal slab.

12. The device of claim 9, wherein the at least one defect portion ranges from a defect point to a defect region that comprises a plurality of defect points.

13. The device of claim 9, wherein the at least one defect portion comprises at least one of a lack of inclusions, inclusions of different sizes, inclusions of different locations, and inclusions of different shapes.

14. In a communications device capable of receiving data from and transmitting data to another communications device, the communications device comprising an acoustical wave system enabling acoustical waves to pass through the system via a micro/nano-mechanical acoustical device, the acoustical wave system comprising:

a phononic crystal acoustic wave medium disposed between an input transducer and an output transducer, the acoustical wave medium enabled to allow acoustic waves to propagate between the transducers, the input transducer configured to excite the acoustic wave medium and the output transducer configured to receive acoustical wave excitation energy;

the acoustic wave medium comprising a plurality of phononic crystal plate sections each containing a multi-dimensional periodic array of empty inclusions creating a phononic band gap, the periodic array of inclusions being disposed so that only acoustic waves of predetermined frequency or range of frequencies to propagate through the acoustic wave medium;

the acoustic wave medium being sized and shaped to contain acoustical waves within the interior volume space of the acoustic wave medium; and

the acoustic wave medium comprising at least one defect region disposed among the periodic array of empty inclusions, the defect region capable of allowing acoustic waves to propagate through the defect region.

15. The acoustical wave system of claim 14, wherein the acoustical wave system forms at least a part of a resonator or filter component in the communications device.

16. The acoustical wave system of claim 14, wherein the multi-dimensional periodic array of empty inclusions are disposed to form a boundary with the at least one defect region.

17. The acoustical wave system of claim 14, wherein the multi-dimensional periodic array of empty inclusions comprise a series of holes formed on exterior surface of the acoustic wave medium.

18. The acoustical wave system of claim 14, wherein the at least one defect region is a linearly-shaped defect region that is disposed intermediate two multi-dimensional periodic array of empty inclusions.

19. The acoustical wave system of claim 14, further comprising a first anchor and a second anchor, the first anchor located proximate to a first end of the acoustic wave medium and the second anchor located proximate the second of the acoustic wave medium, the first anchor and the second anchors situated beneath an exterior surface of the acoustic wave medium and having approximately equal heights to raise the acoustic wave medium above a void area defined beneath the acoustic wave medium so that the acoustic wave medium forms a membrane supported by the anchors, and wherein the anchors are situated away from the phononic crystal plate sections.

20. The acoustical wave system of claim 14, wherein the plurality of phononic crystal plate sections contain at least one of the same periodicity arrangement, a different periodicity arrangement, and a heterogeneous structure that comprises various materials.

21. The acoustical wave system of claim 14, wherein the phononic crystal acoustic wave medium comprises silicon and the multi-dimensional periodic array of empty inclusions are configured in an at least one of a triangular lattice, a square lattice, a hexagonal lattice, or a polygonal lattice.

22. The acoustical wave system of claim 14, wherein the phononic crystal acoustic wave medium comprises a plurality of layered materials.

23. The acoustical wave system of claim 14, wherein the phononic crystal wave medium is configured to operate in at least one of a low frequency range of frequencies below about 1 megahertz and in a high frequency range of frequencies above about 1 megahertz.

24. The acoustical wave system of claim 14, wherein the input and output transducers are located at least one of proximate the phononic crystal plate sections, proximate the defect region, and on the at least one defect region in an integrated fashion.

25. A micro/nano-mechanical acoustical device, the device comprising:

a slab plate sized and shaped to confine acoustical waves within the interior volume of the slab plate;

the slab plate comprising a phononic crystal region and a non-periodic region, the phononic crystal region comprising a periodic array of empty inclusions creating a phononic band gap and proximately situated to the non-periodic region and configured to bound acoustical waves in the non-periodic region, and the non-periodic region configured to allow the acoustic waves to propagate therethrough.

26. The micro/nano-mechanical acoustical device of claim 25, further comprising:

a first anchor and a second anchor respectively disposed at opposing ends of the slab plate, the first and second anchors sized and shape to elevate the slab plate above a void space;

a first transducer and a second transducer, both disposed proximate the slab plate, the first transducer to provide the acoustic waves to excite the non-periodic region and the second transducer to receive acoustic wave energy based on excitation of the non-periodic region; and

wherein the phononic crystal region has multiple lattice periodic arrays that generally bound the non-periodic region.

27. The micro/nano-mechanical acoustical device of claim 25, wherein the periodicity of the phononic crystal region is configured to enable the non-periodic region to resonate at a predetermined frequency or in a predetermined frequency range.

28. The micro/nano-mechanical acoustical device of claim 25, wherein the phononic crystal region comprises phononic crystal structures having varied periodicity characteristics.

29. The micro/nano-mechanical acoustical device of claim 25, further comprising a second slab plate sized and shaped to confine acoustical waves within the interior volume of the slab, the second slab plate coupled to the slab plate enabling the slab plate and the second slab plate to form a multi-stage acoustical wave device.

30. The micro/nano-mechanical acoustical device of claim 25, wherein the phononic crystal region is configured to have periodicity characteristics to control frequency of acoustic waves passing through the slab plate and the non-periodic region.

31. The micro/nano-mechanical acoustical device of claim 25, wherein the non-periodic region is configured to have a linear shape with opposing ends stretching to opposing ends of the slab plate and is disposed intermediate the phononic crystal region.