“…In fact, fiber-optic F-P sensors can be divided into intrinsic and extrinsic sensors [ 11 , 12 , 13 , 14 ], and at present, the latter can be considered as the most extensive and popular fiber-optic F-P sensors owing to their simple structure, easy design and manufacturing process, and so on [ 15 , 16 , 17 , 18 ]. Additionally, extrinsic sensors have been mainly used in any research field needing acoustic sensing technology [ 19 , 20 , 21 , 22 , 23 ]. In fact, PDs can instantly compress surrounding media, thereby making surrounding media vibrate, which can produce acoustic signals [ 6 , 7 ].…”