A fibre-optic ultrasound sensor of simple fabrication.

The small size, high sensitivity, and immunity to electromagnetic interference of fibre-optic ultrasound sensors make them highly attractive for applications in biomedical imaging and metrology. Typically, such sensors rely on optically resonant structures, such as Fabry-Perot cavities, that require elaborate fabrication techniques. Here, an alternative fibre-optic ultrasound sensor is presented that comprises a simple deformable and reflective structure that was deposited using simple dip-coating. Interrogation with a laser Doppler vibrometer demonstrated how this sensor achieved a sensitivity, signal-to-noise ratio, and noise-equivalent pressure that outperformed piezoelectric hydrophones, whilst offering a highly miniature form factor, turn-key operation, and simple fabrication.