The wavelength swept laser (WSL) is a promising optical source in optical coherence
tomography, optical fiber sensor, and optical beat source generation. It is demonstrated by employing a
narrowband wavelength-scanning filter, such as a fast rotating polygonal-scanner-filter, a diffraction
grating on a galvo-scan mirror, or a fiber Fabry-Perot tunable filter (FFP-TF). In this manuscript, we
present our researches on the dynamic fiber-optic sensors. Two kinds of WSLs are used to demonstrate
the dynamic measurement in the fiber-optic sensors. One is the WSL using a polygon-scanner-based
wavelength filter and the other is the Fourier domain mode-locked (FDML) WSL using a FFP-TF. The
dynamic fiber Bragg grating (FBG) sensor interrogation up to 2 kHz by using the WSL with a polygonscanner-
based wavelength filter is reported. And by using the FDML WSL with a FFP-TF, we
demonstrate a resonance FBG sensor interrogation. As another application of the WSL, we successfully
measure a dynamic modulation frequency of the applied electric field using a nematic liquid crystal
Fabry-Perot etalon.
A dual-wavelength tunable fiber laser is demonstrated using two polymer waveguide Bragg gratings (PWBGs) as a wavelength tunable filter. The wavelength tuning in the laser could be achieved by changing the applied electrical power to the PWBG. The interval of dual wavelength can be tuned by 18.9 nm for the maximum applied electrical power of 100 mW. The corresponding frequency range is 2.375 THz. The variation of the lasing wavelength is linearly proportional to the applied electrical power. The side mode suppression ratio of the dual wavelength laser has more than 35 dB.
We report a performance comparison of fiber Bragg gratings (FBGs) sensor interrogation using two kinds of
wavelength swept lasers. In a wavelength swept laser with a fiber Fabry-Perot tunable filter (FFP-TF), the reflected
signal from the FBGs in temporal domain has a nonlinear response with respect to the sinusoidal modulation signal. The
output of the time delay for the strained FBGs sensor array in the wavelength swept laser with FFP-TF has different
slope coefficient for each FBGs, while the reflected output of the strained FBGs in the wavelength swept laser with
polygon scanning filter has same slope coefficient for each FBGs.
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