Novel FBG triangular filter for interrogating a FBG sensor in dynamic strain measurement

We demonstrate the fabrication and the application of an in-fiber triangular filter (T-filter) based on a linearly chirped and apodized fiber Bragg grating (FBG). The theoretical analysis shows that this type of FBG T-filter has a good response in the demodulation of a wavelength-matched FBG sensor. For the first time to our knowledge, such an FBG T-filter has been realized in our laboratory, and utilized to interrogate the signal of dynamic strain by a specially designed measurement scheme. Experimental results have proved that the system has a good performance in the measurement of dynamic strain. Because of its compactness and passiveness, such type of the device can be integrated as a portable demodulation module.