Interferometer-Based Distributed Optical Fiber Sensors in Long-Distance Vibration Detection: A Review

Distributed optical fiber sensing system based on a semiconductor laser with optical injection

“…When an external disturbance acts on the sensing fiber, the length of the fiber (strain effect), refractive index of the fiber core (elastic-optical effect), and diameter of the fiber core (Poisson effect) can change [10], thereby affecting the phasevariation of the light in the fiber. Injecting light with phase-variations into S-SL will cause changes in the number of photons and carriers in S-SL.…”

Detection and Recognition of Voice Commands by a Distributed Acoustic Sensor Based on Phase-Sensitive OTDR in the Smart Home Concept

“…In this paper, we propose a method for registering voice commands using a distributed fiber-optic sensor. Distributed optical fiber sensing technologies have become widespread nowadays [8][9][10]. Rayleigh scattering sensors, which operate on the principle of phase-sensitive optical reflectometry in the time domain, are the most sensitive to acoustic frequency fluctuations.…”

“…Various schemes for their construction have been proposed, including those based on fiber interferometers, including weak Fiber Bragg Gratings (wFBGs), and those based on phase-sensitive optical reflectometers in the time domain (φ-OTDR), which are commonly used as distributed acoustic sensors (DAS) [15]. A distributed fiber-optic microphone based on φ-OTDR is a promising technology that allows for the recording of acoustic disturbances, including speech, along a sensing fiber with a high resolution of 10 m [16] and in a wide frequency band [10] all over large objects and locations with lengths of up to 80 km. A distributed fiber microphone based on φ-OTDR can be used as an independent system to obtain information about speech signals and their coordinates.…”