Distributed Fiber Voice Sensor Based on Phase-Sensitive Optical Time-Domain Reflectometry

A fiber-optic phase-sensitive optical time-domain reflectometry ('-OTDR) distributed sensing system has been proposed and demonstrated for human-voice detecting and reproducing applications. The fiber strain induced by the voice is ultra small (just a few n"); thus, the change of related Rayleigh backscattering light intensity and phase are much too small for effective detection based on the conventional fiber '-OTDR system. Utilizing the flat-packaged fiber design, the strengthened '-OTDR system shows better performance with higher signal-to-noise ratio (SNR) up to 35 dB. The audio frequency and amplitude response have been investigated. The multiplexing capability of this distributed optical fiber microphone also has been proved with 1.2-km sensing range and 5-m spatial resolution.