Curved phononic crystal waveguide

Patent metadata

Field	Value
Publication number	US-11244667-B1
Application number	US-201916258439-A
Country	US
Kind code	B1
Filing date	Jan 25, 2019
Priority date	Jan 26, 2018
Publication date	Feb 8, 2022
Grant date	Feb 8, 2022

Abstract

A curved phononic waveguide. In some embodiments, the curved phononic waveguide includes a sheet including a plurality of standard reflectors and a plurality of divergent reflectors. Each of the standard reflectors is associated with a respective grid point of a grid defined by a plurality of intersecting lines, each grid point being a respective intersection of two of a plurality of intersecting lines, the grid being locally periodic to within 5%, and having a local grid spacing. Each of the standard reflectors has a center separated from the respective grid point of the standard reflector by at most 1% of the grid spacing. The divergent reflectors define a waveguide among the standard reflectors, each of the divergent reflectors being an absent reflector or a reflector that is smaller than one of the standard reflectors.

First claim

What is claimed is:

1. A phononic waveguide, comprising:
a sheet,
the sheet including:
a plurality of standard reflectors, each of the standard reflectors being associated with a respective grid point of a grid defined by a plurality of intersecting lines, each grid point being a respective intersection of two lines of the plurality of intersecting lines, the grid being locally periodic to within 5%, and having a local grid spacing, each of the standard reflectors having a center separated from the respective grid point of the standard reflector by at most 1% of the grid spacing,
a plurality of divergent reflectors, each associated with a respective grid point, the divergent reflectors defining a waveguide among the standard reflectors, each of the divergent reflectors being an absent reflector or a reflector that is smaller than one of the standard reflectors,

the waveguide having a centerline with a radius of curvature, at a first point along the waveguide, of less than 1,000 times a minimum separation between adjacent reflectors of the plurality of standard reflectors.

2. The phononic waveguide of claim 1 , wherein the grid is a square grid.

3. The phononic waveguide of claim 1 , wherein:
the grid is defined by:
a plurality of concentric arcs, and
a plurality of radial lines,

a first arc of the plurality of concentric arcs is the centerline of the waveguide,
successive concentric arcs of the plurality of concentric arcs have radii differing by the local grid spacing at the first point, and
successive radial lines of the plurality of radial lines have a separation at the centerline of the waveguide equal to the grid spacing at the first point.

4. The phononic waveguide of claim 3 , wherein:
each of the standard reflectors is a hole in the sheet having a radius differing from a standard hole radius by at most 5%
each of the divergent reflectors is separated from the centerline of the waveguide by a transverse offset distance,
each of the divergent reflectors is:
a hole having a reduced radius smaller than the standard hole radius, the reduced radius differing by at most 5% from a radius determined by a waveguide profile radius function evaluated at the transverse offset distance, or
an absence of a reflector.

5. The phononic waveguide of claim 4 , wherein each of the divergent reflectors is:
a hole, when the waveguide profile radius function evaluated at the transverse offset distance exceeds a threshold radius value, and
an absence of a reflector otherwise.

6. The phononic waveguide of claim 5 , wherein the waveguide profile radius function is a piecewise constant function.

7. The phononic waveguide of claim 6 , wherein the waveguide profile radius function returns a first value when the transverse offset distance is less than a threshold offset distance, the threshold offset distance being less than the grid spacing at the first point.

8. The phononic waveguide of claim 4 , wherein the waveguide profile radius function is a Lorentzian function.

9. The phononic waveguide of claim 4 , wherein the waveguide profile radius function is function that is everywhere piecewise Lorentzian or piecewise constant.

10. The phononic waveguide of claim 1 , wherein:
the grid is defined by:
a first plurality of parallel, straight lines, and
a second plurality of parallel, straight lines,

successive lines of the first plurality of parallel, straight lines are separated by the grid spacing at the first point, and
successive lines of the second plurality of parallel, straight lines are separated by the grid spacing at the first point.

11. The phononic waveguide of claim 10 , wherein:
each of the standard reflectors is a hole in the sheet having a radius differing from a standard hole radius by at most 5%
each of the divergent reflectors is separated from the centerline of the waveguide by a transverse offset distance,
each of the divergent reflectors is:
a hole having a reduced radius smaller than the standard hole radius, the reduced radius differing by at most 5% from a radius determined by a waveguide profile radius function evaluated at the transverse offset distance, or
an absence of a reflector.

12. The phononic waveguide of claim 11 , wherein each of the divergent reflectors is:
a hole, when the waveguide profile radius function evaluated at the transverse offset distance exceeds a threshold radius value, and
an absence of a reflector otherwise.

13. The phononic waveguide of claim 12 , wherein the waveguide profile radius function is a piecewise constant function.

14. The phononic waveguide of claim 13 , wherein the waveguide profile radius function returns a first value when the transverse offset distance is less than a threshold offset distance, the threshold offset distance being less than the grid spacing.

15. The phononic waveguide of claim 11 , wherein the waveguide profile radius function is a Lorentzian function.

16. The phononic waveguide of claim 11 , wherein the waveguide profile radius function is function that is everywhere piecewise Lorentzian or piecewise constant.

17. The phononic waveguide of claim 10 , wherein a line of the first plurality of parallel, straight lines is perpendicular to a line of the second plurality of parallel, straight lines.

18. The phononic waveguide of claim 1 , wherein the local grid spacing at the first point is greater than 3 microns and less than 30 microns.

19. The phononic waveguide of claim 1 , wherein each of the standard reflectors is a cylindrical hole having a radius greater than 0.20 times the local grid spacing at the first point and less than 0.49 times the local grid spacing at the first point.

20. The phononic waveguide of claim 1 , wherein the sheet has a thickness greater than 10 nm and less than 100 microns and the sheet comprises, as a major component, a material selected from the group consisting of crystalline silicon, silicon carbide (SiC), aluminum nitride (AlN), diamond, glass, silicon nitride, quartz, and combinations thereof.

21. The phononic waveguide of claim 1 , wherein the sheet is composed of a material having a bulk propagation loss, for sound waves at a frequency greater than 10 MHz and less than 100 GHz, of less than 1 dB/micron, wherein the sound waves are waves of a kind selected from the group consisting of longitudinal waves, surface waves, Lamb waves, Love waves, Stoneley waves, Sezawa waves, and combinations thereof.

Assignees

• Hrl Lab Llc

Inventors

• Perahia Raviv
• Bregman Jeremy
• Patel Amit M
• Meenehan Sean M
• Huang Lian X
• Sorenson Logan D

Classifications

• G10K11/24

  for conducting sound through solid bodies, e.g. wires · CPC title

• G10K11/28 Primary

  using reflection, e.g. parabolic reflectors · CPC title

• G10K11/04

  Acoustic filters {; Acoustic resonators} · CPC title