Highly reliable strain-tuning of an Erbium-doped fiber laser for the interrogation of multiplexed Bragg grating sensors

Hybrid wavelength-time domain interrogation system for multiplexed fiber Bragg sensors using a strain-tuned erbium-doped fiber laser

“…Transients during switching from one wavelength band to another are due to relaxation oscillations in the laser during the optical switching and they cause the wavelength interval to have a small dead-time before a proper interrogation can start and are responsible for most of the oscillations in the photo-detected signal. Since such noise can not be eliminated, only minimized, it would explain why the resolution value is almost the twice the one reported in the system using only one DTG [9]. During the measurements of temperature in the motor, the acquisition rate of the photo-detected signal was 8mHz.…”

“…This is a method that inherits the properties of the tunable-filter method interrogation technique using a lock-in amplifier. The set of algorithms provides a good discrimination of the peak of the spectrum without the need to modulate the Bragg wavelength with a dither [9] and uses the detection of the zero-crossing point in the first derivative signal associated to the peak of the BGS spectrum. The RFBG are kept without perturbations and can be used as wavelength references.…”

“…However, such techniques are still limited by physical constraints related to deformation capacity of a standard FBG which comprises 1% of its length. Recently, the use of high-strength draw-tower fiber Bragg gratings (DTG) to tune an EDF laser overcame this limitation by allowing a five-fold increase in the deformation capacity of the tunable FBG [9]. In this paper, another improvement to this technique is proposed using two DTG with different Bragg wavelengths bonded in the same PZT mount apparatus to be stretched simultaneously.…”

A linearity interrogation technique with enlarged dynamic range for fiber Bragg grating sensing

“…However, for a practical system, it is not feasible to use conventional monochromators or optical spectrum analyzers for the measurement of a small Bragg wavelength shift owing to their bulkoptical nature, size and lack of ruggedness and, in some cases, limited resolution [4]. Because of application demands, different techniques have been developed for these sensors, major of them based on filter, interferometer or spectroscopic analysis [5,6], such as linear edge filters [7][8][9], Fabry-Perot filter [10], acousto-optic tunable filter [11], Mach-Zender interferometer [12], Michelson interferometer [13], Fourier transform spectroscopy [14] and CCD-based spectrometer [15], expect for tunable laser [16,17]. These techniques can be used for multiple sensors, but they are not very good solution because they require expensive components and equipments to the measurements and their environmental-related instability remains a difficult problem, or their frequent need for recalibration.…”

Bi 2 O 3 -based erbium doped fiber laser with over 110 nm tunable range for fiber sensor sources

“…And allocating different wavelengths to each FBG sensors, it is easily multipled sensing point. As broadband light sources, Erbium doped fiber laser is studied for multiplexed FBG sensors [2,3]. The available sensing point is limited for the light source tenability.…”