Fiber-optic Bragg grating strain sensor with drift-compensated high-resolution interferometric wavelength-shift detection

Abstract

The operation of a fiber Bragg grating strain sensor system that uses interferometric determination of strain-induced wavelength shifts and incorporates a reference channel to compensate for random thermal-induced drift in the output is described. This system is shown to be capable of resolving sub-microstrain changes in the quasi-static strain applied to a grating and has a resolution of ~6 x 10(-3) microstrain/ radicalHz at a strain perturbation frequency of 1 Hz.

Ultrasonic hydrophone based on short in-fiber Bragg gratings

“…This utilized a ramped lithium nio-bate phase modulator ͑accurately set to produce a 2 peak-to-peak phase excursion͒ to frequency shift the light in one arm of an unbalanced Mach-Zehnder interferometer ͑MZI͒ and thus allowed the use of heterodyne signal processing. 18,19 Light from a pigtailed superluminescent diode ͑Superlum, Moscow͒, giving an output power of 1 mW centered at 824 nm with a bandwidth of Ϸ42 nm, was launched into the unbalanced MZI; hence a channeled spectrum was created at the interferometer's outputs that was incident on the grating. Incorporated in one arm of the MZI was the phase modulator.…”

Thin bonding wires temperature measurement using optical fiber sensors

“…Several techniques based on simple interferometry [9], Fabry-Perot filters [10], matched gratings [6], acoustic-optic tunable filters [18], tunable lasers, long period gratings [19,8], Sagnac loops based on the chirped fiber Bragg gratings [20] or multiport fiber Mach-Zehnder interferometer for multi sensors interrogation [7] can be used to collect data from FBGs [3].…”

Mode-Locked Erbium-Doped Fiber Lasers Using 45° Tilted Fiber Grating

“…Fiber gratings, firstly demonstrated in 1970s [19], have been extensively investigated from the fundamental theory to applications in optical communication [20], nonlinear signal processing [21], various types of sensors and lasers [22], [23]. With its inherent fiber format, the fiber grating devices have been intensively applied as reflection mirrors of fiber laser cavity [24].…”