Symbiosis-Michelson Interferometer-Based Detection Scheme for the Measurement of Dynamic Signals

A symbiosis-Michelson interferometer (SMI)-based detection scheme is proposed and experimentally demonstrated. The SMI comprises a 3 × 3 coupler, two FBGs with different center wavelengths, and a common reference arm. Two MIs share a 3 × 3 coupler and a reference arm. The sensing part is the fiber between the two FBGs. The sensitivity of the sensor is high because of its long sensing fiber. Light beams reflected from two MIs pass the same leading fiber and the reference arm, so the undesirable external perturbation can be removed by calculating the difference of two outputs. Thus, the SMI is insensitive to interfering signals. An SMI-based vibration sensor and an SMI-based acoustic sensor fabricated by a 3D printer are experimentally investigated. For the SMI-based vibration sensor, an OPD sensitivity of 1274 nm/g is obtained. The acceleration resolution of the sensor is <;0.78 mg. A 19-kHz acoustic signal is detected successfully by the SMI-based acoustic sensor. SMI-based vibration/acoustic sensors with different performances can be fabricated conveniently. The detection scheme has properties of high sensitivity, robustness against surrounding environment instabilities, and wide frequency response range.