We report a novel demodulation scheme for the detection of small Bragg wavelength shifts in a fiber Bragg grating strain sensor by exploiting the optical feedback reflected from the grating structure back into a 1310 nm laser diode integrating a photodiode. The dynamic strain generated by a mechanical vibrator is applied transversely to the fiber Bragg grating and the desired longitudinal strain values inferred from the detected sawtooth-like optical feedback signals. Preliminary results demonstrate the feasibility of this demodulation technique for strain measurement which could be further extended to fiber Bragg grating-based sensors for the detection of different measurands in general.
Bibliographical noteInstrumentation and Measurement Technology Conference, 2006 (IMTC 2006), 24-27 April 2006, Sorrento (IT).
- Fiber Bragg grating sensor
- dynamic strain measurement
- optical feedback interferometry