Sensitive, small, broadband and scalable optomechanical ultrasound sensor in silicon photonics

Wouter Westerveld, Md. Mahmud-Ul-Hasan, Rami Shnaiderman, Vasilis Ntziachristos, Xavier Rottenberg, Simone Severi, Veronique Rochus

Research output: Contribution to journalArticleScientificpeer-review

52 Citations (Scopus)
1 Downloads (Pure)

Abstract

Ultrasonography 1 and photoacoustic 2,3 (optoacoustic) tomography have recently seen great advances in hardware and algorithms. However, current high-end systems still use a matrix of piezoelectric sensor elements, and new applications require sensors with high sensitivity, broadband detection, small size and scalability to a fine-pitch matrix. This work demonstrates an ultrasound sensor in silicon photonic technology with extreme sensitivity owing to an innovative optomechanical waveguide. This waveguide has a tiny 15 nm air gap between two movable parts, which we fabricated using new CMOS-compatible processing. The 20 μm small sensor has a noise equivalent pressure below 1.3 mPa Hz −1/2 in the measured range of 3–30 MHz, dominated by acoustomechanical noise. This is two orders of magnitude better than for piezoelectric elements of an identical size 4. The demonstrated sensor matrix with on-chip photonic multiplexing 5–7 offers the prospect of miniaturized catheters that have sensor matrices interrogated using just a few optical fibres, unlike piezoelectric sensors that typically use an electrical connection for each element.

Original languageEnglish
Pages (from-to)341–345
Number of pages5
JournalNature Photonics
Volume15
Issue number5
DOIs
Publication statusPublished - 2021
Externally publishedYes

Keywords

  • silicon photonics
  • Ultrasound
  • optomechanics

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