Fiber-optic Fabry-Perot temperature sensor using a low-coherence light source

Abstract

Abstruct-An interferometric fiber-optic sensor using a light emitting diode (LED) as the optical source is analyzed and demonstrated. The sensor arrangement employs two Fabry-Perot interferometers (FPl's) in series, one for sensing and one which serves as a reference. The optical output from the LED is spectrally modulated by reflection from the sensing FPI. Then, reflection or transmission by the reference FPI produces an interferometric beat response similar to that observed when a laser is used with the sensing interferometer alone. Best fringe visibility is obtained when the optical path lengths of the two interferometers are matched, and the fringes disappear when the path length difference becomes substantially greater than the coherence length of the LED. The predicted behavior is confirmed by experiments in which the temperature of the sensor FPI is changed while that of the reference is held constant.

Low-coherence Michelson interferometric fiber-optic multiplexed strain sensor array: a minimum configuration

“…The new approach differs from previously demonstrated multiplexing schemes [2][3][4][5][6][7][8][9] in that only a cavity-length adjustable fiber-optic ring resonator is needed to generate differential optical paths to match the sensing gauges. In the sensor array, only a single fiber lead supplies both input and output signals, which is advantageous because it greatly reduces the complexity and cost of a low-coherence interferometric multiplexed sensor array.…”

“…[1][2][3][4][5][6][7][8][9] An advantage of this approach compared with using conventional interferometric sensors is well known, in that it can be used to determine a quasi-static measurement such as temperature, pressure, and strain with a corresponding displacement range much larger than one wavelength. Another advantage is that many sensors can be coherently multiplexed onto a single optical signal without the need for relatively complex time or frequency multiplexing techniques.…”

Decoding the spectra of low-finesse extrinsic optical fiber Fabry-Perot interferometers

“…Such fiber coupled interferometers have been demonstrated as highly sensitive and robust sensors for measurement of temperature [1,2], strain [3], pressure [4,5] and acoustic wave [6]. White-light interferometry [7], in which the interferometer is illuminated either by a broadband optical source or a wavelength-tunable laser and its reflected spectrum is analyzed, has shown promising advantages over other interrogation counterparts in terms of demodulation accuracy, absolute measurement and immunity to optical power instability.…”

Multimode excitation-induced phase shifts in intrinsic Fabry–Perot interferometric fiber sensor spectra

“…Fiber-optic Fabry-Perot (FP) interferometric sensors have been extensively studied in the past two decades for measurement of a variety of parameters, such as temperature [1], strain [2,3], pressure [4,5], and acoustic waves [6,7]. Generally, fiber FP sensors can be divided into extrinsic and intrinsic types.…”