Fiber-Optic Accelerometer Using Tilted Grating Inscribed in Depressed Cladding Fibers

We propose and experimentally demonstrate a compact fiber-optic vibration sensor in which a tilted Bragg grating is inscribed in the core of a depressed cladding fiber. The sensor provides resolution up to 2× 10^-2 m/s² and a linear acceleration response between 0.2 and 6.0 m/s², together with a flat frequency response between 1 and 120 Hz. The sensor takes advantage of a cost-effective interrogation scheme by monitoring the total reflection power of the fiber sensor. We use the calibrated output to eliminate the potential light source and fiber loss-induced power fluctuations. The proposed sensing system has been used to measure the vibration of a mechanical damper in electrical transmission lines and the results agree well with those from a commercial sensor.