Self-Referenced Accelerometer Array Multiplexed on a Single Fiber Using a Dual-Pulse Heterodyne Phase-Sensitive OTDR

We report a new type of multiplexed fiber-optic accelerometer array based on a dual-heterodyne-pulse phase-sensitive OTDR technique. This scheme significantly simplifies the structure of fiber accelerometer and can greatly benefit its practical applications. The sensitivity model for the new type accelerometer based on the Rayleigh backscattering is developed for the first time, which shows a great difference from the transmission-type interferometric accelerometer. On a single piece of telecommunication fiber, we demonstrate the multiplexing of three accelerometers separated by 20 m, each with a measured sensitivity of ∼36 rad/g that agrees well with the theoretical analysis. The connecting fiber between accelerometers simultaneously acts as a distributed acoustic sensor, which under proper vibration isolation can be used as a self-reference to suppress system noises. We show that the common-mode noises of the sensor can be suppressed by 35 dB at a frequency of 100 Hz without using additional reference interferometers.