Fiber optic-based laser interferometry array for three-dimensional ultrasound sensing

Ultrasound imaging has been widely used in medical diagnosis due to its noninvasive, radiation-free, and real-time features. Optical resonance-based ultrasound sensors possess high sensitivity and broad bandwidth, but they need to operate in specific laser wavelengths or angles, which restricts their application in array sensing. Non-resonance-based optical sensing arrays did not perform with sufficient bandwidths or frame rates. Here we propose a fiber optic-based ultrasound sensing array with relatively high sensitivity, wide bandwidth, and three-dimensional (3D) sensing capabilities, which is potentially useful in medical imaging. Specifically, we experimentally demonstrated that the optical ultrasound sensor exhibited a noise equivalent pressure of 165 Pa, pressure nonlinearity of < 5%, −3 dB angular uniformity of ±71^◦, and −6 dB bandwidth from ∼ 0 to 27.2 MHz. For 3D sensing capabilities in spherical coordinates, the errors of the radial distance were within 5%, and the errors for the polar and azimuthal angles were within 4^◦ and 2^◦, respectively. This demonstrated the viability and high performance of the array for 3D ultrasound sensing.