Optimization of fiber Bragg grating parameters for sensing applications

Incoherent Optical Frequency-Domain Reflectometry Based on Homodyne Electro-Optic Downconversion for Fiber-Optic Sensor Interrogation

“…Globally, the performance of this I-OFDR reflectometer for RBS characterization is similar to that of conventional I-OFDR systems based on VNA for sensor interrogation [17,42] or in-line monitoring [31], but with the identified limitations of polarization-dependent detection and echoes induced by harmonic distortion. The first can be solved by incorporating polarization switching [43,44] or scrambling [23]; the second represents a deterministic impairment that can be avoided, if necessary, by a previous calibration of the distortion and subsequent equalization.…”

“…Polarization control at the receiver’s side mitigates this problem, but this option is only viable for low ranges. The standard approaches to overcome this issue include the use of polarization-maintaining fiber [43]; the use of depolarizers or polarization scramblers to average the response over polarization at the price of an additional 3 dB power penalty [23]; or the use of polarization switching [43,44]. In our measurements of point reflectors, we implemented polarization switching, as described below.…”

Strain measurement with multiplexed FBG sensor arrays: An experimental investigation

“…Historically, sensing technologies based on Fibre Bragg Grating (FBG) [ 15 ] have been applied to a vast range of applications, such as shape sensing [ 16 , 17 ], healthcare [ 18 ], magnetic field detection [ 19 , 20 ], as well as in the hydrocarbon industry [ [21] , [22] , [23] , [24] ]. More recently, the intrinsic properties of the FBG, such as its low electromagnetic interference (EMI), natural waterproofness, multiplexing capability, small size, acoustic emission capabilities, resistance to high pressures and high temperatures (HPHT), wavelength-encoded characters and linearity with pressure [ [25] , [26] , [27] , [28] ], have been seen as outstanding advantages for using FBG to measure strain, temperature, pressure and ultrasonic waves effectively in a laboratory environment [ [29] , [30] , [31] , [32] ]. This allows for the obtention of a more accurate and complete picture of the rock behaviour, including all responses derived from the heterogeneity and anisotropy of the sample.…”