The acousto-optic technique has been applied to acoustic sensing 1,2 and mapping 3 for over 20 years. A few years ago 4, we proposed the use of a high-finesse Fabry-Pérot cavity to enhance the sensitivity of the method and thus make it viable for low-uncertainty primary acoustic measurement and calibration. Using a plane-wave acoustic resonator, we have carried out a comparison of the acoustic pressure measured by a reciprocity-calibrated standard microphone to the acoustic pressure measured using the acousto-optic method in a Fabry-Pérot optical cavity with a finesse in the range of a few thousand, at an acoustic frequency of 1 kHz. We demonstrate agreement at the percent level, comparable to the uncertainty of the acousto-optic measurement. We believe that there is room for improvement of our acousto-optic measurement and that this early result indicates the viability of acousto-optic methods as an alternative to reciprocity for primary acoustic measurements.
Reschovsky et al. (2025) studied this question.