A theoretical framework is presented for calculating the opto-acoustic response of optical fiber ultrasound sensors with several layers of coating. A harmonic point source generating a spherical wavefront with arbitrary position and frequency is assumed. The fiber is acoustically modeled by a layered cylinder on which spherical waves are scattered. The principle strains on the fiber axis are calculated from the scattering of the acoustic waves and used in a strain-optic model to calculate the phase shift of the guided modes. The theoretical results are compared to experimental data obtained with a sensing element based on a π-phase-shifted fiber Bragg grating and with photoacoustically generated ultrasonic signals.
Veres, I. A., Burgholzer, P., Berer, T., Rosenthal, A., Wissmeyer, G., & Ntziachristos, V. (2015). Characterization of the spatio-temporal response of optical fiber sensors to incident spherical waves. In Physics Procedia (Vol. 70, pp. 155–158). Elsevier. https://doi.org/10.1016/j.phpro.2015.08.078