A fiber optic sensor employs at least two flexural discs that are spaced apart from one another along a central axis. A fiber optic coil is affixed to at least one of the flexural discs. A proof mass is disposed between the flexural discs. A first stop member is disposed between the proof mass and one flexural disc. A second stop member is disposed between the proof mass and the other flexural disc. The first and second stop members are sized to provide space between the proof mass and the corresponding flexural disc to allow for normal motion of the flexural discs, while interfering with movement of the flexural discs to prohibit unwanted extreme motion. The fiber optic sensor can be used for OTDR measurements of acceleration for real-time oilfield monitoring applications as well as other fiber-based interferometric measurement applications. A coupling structure preferably couples the outer edges of the flexible disks, the mass being attached to the coupling structure.