Novel accelerometer realized by a polarization-maintaining photonic crystal fiber for railway monitoring applications.

In this paper, we present a novel accelerometer based on the Sagnac interferometer configuration using a polarization-maintaining photonic crystal fiber (PM-PCF), which has a sensitivity of ~8 pm/G, and a resonant frequency exceeding 2.5 kHz. The proposed accelerometer is capable of functioning with a constant sensitivity in a large frequency range from 0 to 1 kHz which is much wider than many FBG-based accelerometers. Experimental results obtained from a field test in railway monitoring, demonstrate a broader frequency range for the proposed accelerometer compared to that of the FBG based accelerometer and is comparable to the conventional piezoelectric sensor. The abrupt change in the acceleration measured by the sensor aids in locating any defect or crack present on the railway track. To the best of our knowledge, this is the first demonstration of an accelerometer based on a fiber interferometer aimed for the railway industry. The proposed accelerometer operating at high accelerations (>40 G) and capable of functioning at a broad frequency range, shows significant potential in being used in applications which require detection of strong and fast vibrations, especially in structural health monitoring of trains and railway tracks in real time.