Listening to the Underwater Acoustic Based on Fiber-Optic Tweezers Technology

We have explored a new way to achieve ultrasensitive detection of acoustic waves in an aqueous environment based on fiber-optic tweezers technology. Silicon dioxide particle trapped by the piconewton scale’s light force is used as underwater acoustic wave sensors. When the acoustic signal propagates in water, it will cause microscale vibration of the particle in the light trap, resulting in small changes in the distance between the particle and the tip of the fiber optic and a change in the light range difference between the reflected beams, and the original underwater acoustic wave signals are obtained based on the resulting double-beam interference effect. Experiments show that, by collecting the movement information of particle in the optical trap under the influence of acoustic waves, it is possible to listen to acoustic signals with sound power as low as −67.135 dB and real-time monitoring of acoustic signals within the frequency range of 5–4 kHz, with a signal-to-noise ratio (SNR) of up to 72.073 dB. The new underwater acoustic sensing mode proposed in this article can overcome the existing acoustic sensing technology’s limitations and provide a new direction for the sensing field of optical fiber tweezers technology.