Optical fiber acoustic sensors are a kind of acoustic sensors that use optical fibers as light-propagating media or detection units. Compared to traditional electro-acoustic sensors, it features high sensitivity, broad-band frequency response, anti-electromagnetic interference etc, thus very promising for national security, industrial non-destructive testing, medical diagnostics, consumer electronics etc. Optical fiber acoustic sensors are classified, in terms of the coupling mode between acoustic field and light, as indirect and direct coupling types. The former presents some problems such as uneven frequency response, narrower bandwidth, and smaller dynamic range due to the frequency response features of the acoustic coupling materials, while the latter has overcome these shortcomings and thus possesses broad development potential.