2017/10/11 by Deepa Srivastava, Srivastava, Deepa, Bhargab Das +1
Engineering · #Advanced Fiber Optic Sensors #Advanced Photonic Communication Systems #FOS: Physical sciences #Instrumentation and Detectors (physics.ins-det) #Optics (physics.optics) #Photonic and Optical Devices
paper · pdf · doi:10.48550/arxiv.1710.04206
openalex publication_date 2017/10/11 · openalex created_date 2024/04/10 · openalex updated_date 2026/07/28
Interferometric interrogation technique realized for conventional fiber Bragg grating (FBG) sensors is historically known to offer the highest sensitivity measurements, however, it has not been yet explored for π-phase-shifted FBG (πFBG) sensors. This, we believe, is due to the complex nature of the reflection/transmission spectrum of a πFBG, which cannot be directly used for interferometric interrogation purpose. Therefore, we propose here an innovative as well as simple concept towards this direction, wherein, the transmission spectrum of a πFBG sensor is optically filtered using a specially designed fiber grating. The resulting filtered spectrum retains the entire characteristics of a πFBG sensor and hence the filtered spectrum can be interrogated with interferometric principles. Furthermore, due to the extremely narrow transmission notch of a πFBG sensor, a fiber interferometer can be realized with significantly longer path difference. This leads to substantially enhanced detection limit as compared to sensors based on a regular FBG of similar length. Theoretical analysis demonstrate that high resolution weak dynamic strain measurement down to 4 pε/sqrt(Hz) is easily achievable.