Acoustical pressure sensor with photonic waveguide

Patent metadata

Field	Value
Publication number	US-11320303-B2
Application number	US-202016840269-A
Country	US
Kind code	B2
Filing date	Apr 3, 2020
Priority date	Apr 4, 2019
Publication date	May 3, 2022
Grant date	May 3, 2022

Abstract

Embodiments relate to a sensor structure for an acoustical pressure sensor and an opto-mechanical sensor and system that may be used for detecting acoustical pressure waves. Embodiments of a sensor structure for an acoustical pressure sensor include an optical waveguide closed-loop resonator and a plurality of sensor elements. The individual sensor elements of the plurality of sensor elements are configured to be affected by an acoustical pressure wave such that a physical property of the individual sensor element is changed. The optical waveguide closed-loop resonator is arranged at the plurality of sensor elements and associated with each of the individual sensor elements such that a resonance frequency of the optical waveguide closed-loop resonator is shifted due to the affected physical properties of all individual sensor elements. The sensor structure provides a high sensitivity from each sensor element, which is advantageous in e.g. ultrasonic imaging, such as photo-acoustic imaging where the signals typically are low.

First claim

The invention claimed is:

1. A sensor structure for an acoustical pressure sensor, comprising
an optical waveguide closed-loop resonator and
a plurality of sensor elements, wherein the individual sensor elements of the plurality of sensor elements are configured to be affected by an acoustical pressure wave such that a physical property of the individual sensor element is changed; and wherein
the optical waveguide closed-loop resonator is arranged at said plurality of sensor elements and associated with each of the individual sensor elements of the plurality of sensor elements such that a resonance frequency of the optical waveguide closed-loop resonator is shifted due to the affected physical properties of all individual sensor elements of the plurality of sensor elements.

2. A sensor structure according to claim 1 , wherein each of the individual sensor elements comprises a flexible portion and wherein the physical property affected by the acoustical pressure wave is a deformation of the flexible portion of the sensor element.

3. A sensor structure according to claim 2 , wherein the closed-loop optical waveguide resonator associated with individual sensor element of the plurality of sensor elements is attached to the flexible portion such that the closed-loop optical waveguide resonator also deforms upon deformation of said flexible portion.

4. A sensor structure according to claim 2 , wherein a part of the optical closed-loop waveguide associated with the individual sensor elements of the plurality of sensor elements is partially attached to the flexible portion and partially attached to a fixed portion such that a deformation of the flexible portion affects the propagation of the electro-magnetic wave in said part of the optical closed-loop waveguide.

5. A sensor structure according to claim 1 , wherein the plurality of sensor elements is configured with a specific sound receive radiation pattern.

6. A sensor structure according to claim 5 , wherein the plurality of sensor elements is configured to have an acoustical focus in one or two dimensions.

7. A sensor structure according to claim 1 , wherein the plurality of sensor elements form an elongated sensor area.

8. A sensor structure according to claim 7 , wherein the optical waveguide closed-loop resonator comprises at least two parallel portions extending along a longitudinal direction of the elongated shape, wherein at least two parallel portions are connected by loops at ends of the parallel portions, wherein the parallel portions are arranged at the plurality of sensor elements.

9. An opto-mechanical sensor for detecting acoustical pressure waves comprising
at least one sensor structure according to claim 1 ;
at least one optical waveguide arranged for transmitting an electro-magnetic wave to said at least one sensor structure such that part of the spectrum of the electro-magnetic wave is coupled into said optical waveguide closed-loop resonator of the at least one sensor structure.

10. An opto-mechanical sensor according to claim 9 , wherein the sensor comprises a plurality of sensor structures having sensor elements forming elongated sensor areas in an X-Y plane such that each of the elongated sensor areas are elongated in the Y direction and have a length in the Y direction that larger than the wavelength of the acoustical pressure waves to be detected, and wherein each of the plurality of sensor elements of the plurality of sensor structures has an acoustical focus in a Y direction, thereby allowing imaging in an X-Z plane using recordings of the plurality of sensor structures; wherein the Z-direction is the direction of the normal of the X-Y plane.

11. An opto-mechanical sensor according to claim 9 , wherein the sensor comprises a plurality of sensor structures and wherein a single optical waveguide of the at least one optical waveguide is arranged to couple at least part of the spectrum of the electro-magnetic wave into the optical-waveguide closed-loop resonators of the plurality of sensor structures.

12. An opto-mechanical sensor according to claim 9 , wherein the sensor comprises at least two sensor structures and at least two optical waveguides, and wherein the sensor structures and optical waveguides are arranged so that there is one optical waveguide for transmitting an electro-magnetic wave to each sensor structure, and wherein the opto-mechanical sensor further comprises a
wavelength division multiplexing (WDM) unit for splitting the bandwidth of electro-magnetic waves transmitted to the opto-mechanical sensor into a plurality of wavelength channels such that each individual sensor structure of the at least two sensor structures may be addressed by one individual wavelength channel.

13. An opto-mechanical sensor according to claim 12 , wherein the WDM unit comprises a spectral filter having channels with wavelength-bandwidths that are wider than the free-spectral range of the optical waveguide closed-loop resonators of the at least two sensor structures, such that at least one channel contains at least one resonance of an individual optical waveguide closed-loop resonator of the at least two sensor structures.

14. An opto-mechanical sensor system comprising
an opto-mechanical sensor according to claim 9 ;
at least one light source for generating an electro-magnetic wave into the at least one optical waveguide of the opto-mechanical sensor; and
at least one photo-detector for detecting an electro-magnetic wave that has been transmitted in the optical waveguide of the opto-mechanical sensor.

15. An opto-mechanical sensor system according to claim 14 , wherein said at least one light source is configured to emit light of a first wavelength that is tuned to a flank of the optical resonance frequency of the optical waveguide closed-loop resonators of the at least one sensor structure.

Assignees

• Imec Vzw
• Univ Leuven Kath

Inventors

• Westerveld Wouter Jan
• Jansen Roelof
• Rottenberg Xavier
• Rochus Veronique

Classifications

• G01H9/004 Primary

  using fibre optic sensors (light guides per se G02B6/00, acousto-optical devices specially adapted for gating or modulating in optical wave guides G02F1/125) · CPC title