Multipoint acoustic impedance sensing based on frequency-division multiplexed forward stimulated Brillouin scattering
Zhou Zheng, Zhengying Li, Xuelei Fu, Lixing Wang, Honghai Wang
Abstract
Acoustic impedance sensing based on forward stimulated Brillouin scattering (FSBS) in fiber has attracted the attention of researchers in recent years. Here, we propose a novel, to the best of our knowledge, multipoint sensing scheme based on FSBS, which explores frequency-division multiplexing. Since the resonance center frequencies of the FSBS-invoked acoustic modes are dependent on the fiber diameter, different fiber sections can be differentiated using carefully selected representative peaks in the FSBS spectrum. With a Sagnac loop structure, continuous-wave light is adopted for FSBS excitation, reducing the required fiber length for efficient opto-acoustic interaction. By evaluating the linewidths of representative peaks, simultaneous acoustic impedance sensing at multiple locations is realized with 0.8 m sensor size.