In the vast ocean, sound waves are so far the only form of energy transfer that can achieve long-distance transmission, and sonar equipment is the "wind ear" in the maritime military field, which can detect sound ripples from submarines, ships, etc. at a long distance . However, with the development of underwater acoustic countermeasure and anti-countermeasure technology, especially the emergence of quiet submarines, the noise frequency has been reduced to about 100 Hz, and the noise level is even lower than the background noise of the ocean. Facing the "deep breath" of these "silent killers" in the ocean, traditional piezoelectric hydrophones seem quite powerless.
In recent years, with the development of fiber optic sensing technology, fiber optic hydrophones based on the principle of fiber optic sensing have gradually attracted the attention of military research fields in various countries. Compared with traditional piezoelectric hydrophones, fiber optic hydrophones, as a new type of underwater acoustic detection device, have higher sensitivity, good very low frequency response, wide response frequency bandwidth, and large dynamic range. Long-distance signal transmission. These technical advantages make the fiber optic hydrophone have unique technical advantages in the detection of low-noise and low-frequency underwater acoustic signals, making it more likely to become the "nemesis" of quiet ships.
So, what is the reason why the fiber optic hydrophone has such outstanding technical advantages? This first needs to start with the technical principle of the fiber optic hydrophone.
Technical principle of fiber optic hydrophone
The fiber optic hydrophone is a sensor that uses the underwater acoustic signal to act on the optical fiber to cause changes in the intensity, polarization, and phase of the light propagating in the optical fiber to sense the underwater acoustic signal. After decades of research and development, there are two mainstream technical solutions for fiber optic hydrophones: interference fiber optic hydrophones and fiber grating hydrophones.
