Recent Advancements in Rayleigh Scattering-Based Distributed Fiber Sensors

Abstract

Recently, Rayleigh scattering-based distributed fiber sensors have been widely used for measurement of static and dynamic phenomena such as temperature change, dynamic strain, and sound waves. In this review paper, several sensing systems including traditional Rayleigh optical time domain reflectometry (OTDR), Φ-OTDR, chirped pulse Φ-OTDR, and optical frequency domain reflectometry (OFDR) are introduced for their working principles and recent progress with different instrumentations for various applications. Beyond the sensing technology and instrumentation, we also discuss new types of fiber sensors, such as ultraweak fiber Bragg gratings and random fiber gratings for distributed sensing and their interrogators. Ultimately, the limitations of Rayleigh-based distributed sensing systems are discussed.

Photonic Sensors

“…On the other hand, optical fiber distributed sensors, key OFS technology based on linear scattering (Rayleigh) and non-linear scattering (Raman, Brillouin) are the more relevant used techniques [50,51]. Two recent cases, one based on a hybrid configuration to measure very high temperatures and another based on speckle for on-bed patient measurements, will be very briefly reviewed below.…”

Sensing Using Light: A Key Area of Sensors

“…For Point and quasi-distributed measurements, fiber-optic microstructure sensors including Fiber Bragg grating (FBG), long-period fiber grating, Fabry-Pérot interferometer sensors, Mach-Zehnder interferometer sensors, Michelson interferometer sensors, and Sagnac interferometer sensors are widely used [ 49 ]. On the other hand, optical fiber distributed sensors, key OFS technology based on linear scattering (Rayleigh) and non-linear scattering (Raman, Brillouin) are the more relevant used techniques [ 50 , 51 ]. Two recent cases, one based on a hybrid configuration to measure very high temperatures and another based on speckle for on-bed patient measurements, will be very briefly reviewed below.…”

“…Acquiring an early indication of structural or mechanical problems allows operators to better plan for maintenance, possibly operate the machine in a de-rated condition rather than taking the unit off-line, or in the case of an emergency, shut the machine down to avoid further damage. To build an accurate Structural Health Monitoring (SHM) system in the wind turbine, photonic sensors based on fiber technology installed on/in the blades are essential [ 41 , 42 , 43 , 44 , 45 , 46 , 47 , 48 , 49 , 50 , 51 , 52 , 53 , 54 , 55 ]. Even though several fiber optic transducer technologies are being employed to constitute the “nerve” part of the smart fiber optic sensor system, here, we will only briefly mention one based on FBGs ( Figure 8 ).…”

2D Temperature Field Reconstruction Using Optical Frequency Domain Reflectometry and Machine-Learning Algorithms

“…[ 1 , 2 ]. In the latter case, the physical impact is extracted by processing the backscattered Rayleigh, Brillouin, or Raman signals [ 1 , 3 ]. When monitoring relatively compact devices and structures (e.g., elements of robotic systems [ 4 , 5 ], composite materials for the automotive and aerospace industries [ 6 , 7 , 8 ], etc.)…”