High-sensitivity MZI strain sensor with separation of cladding mode field and strain concentration area

This article proposes a wave structure MZI strain sensor (Wavy-MZI), which utilizes the wave structure to spatially separate the strain concentration area of the optical fiber from the cladding mode field offset area, concentrating the strain on the inner side of the wave structure while offsetting the cladding mode field of the optical fiber to the outer side of the wave structure. During the strain process, the displacement zone of the cladding mode is subjected to extremely weak strain, which significantly reduces the decrease in the effective refractive index of the cladding mode during the strain process, thereby increasing the change in the effective refractive index difference between the core mode and the cladding mode, achieving a highly sensitive MZI strain sensor. The experimental results show that the strain sensitivity of Wavy-MZI can reach up to 166.64 pm/µε, demonstrating great potential for application in weak strain detection.