We have demonstrated suppression of low-frequency fluctuations of backscattered Rayleigh radiation in distributed fiber
optical sensors with chaotic single-longitudinal mode DFB and multi-longitudinal mode FP lasers subjected by
incoherent optical feedback. Significant decreasing of Rayleigh power variations up to 15-20 dB for 10-1000 Hz
frequency interval was recorded for both chaotic lasers. It was shown that chaotic DFB laser also efficiently restrain
stimulated Brillouin scattering in the test fiber. The results have important consequences for distributed fiber optical
sensors, which utilized Rayleigh signals.
The paper presents distributed fiber optic bending sensor for petroleum hydrocarbon detection based on COFDR technique. Sensitive polymer, which effectively swells under hydrocarbon influence, was employed in order to introduce bending losses in hydrocarbon presence. In this work we used lumped reflectors, namely fiber Bragg gratings, placed between distributed sensitive elements. Proposed design of the sensor utilises the principle of truly distributed detection with discrete localisation of perturbation. We have demonstrated that the COFDR technique with bending based chemical sensor is capable to detect hydrocarbon presence within a few minutes for 20-cm perturbation-length with spatial resolution up to 0.5 meters.
The paper presents the theoretical and experimental results of the strain- and temperature gradient measurement with differential twin Bragg grating sensor. It is shown that this technique could also be used for temperature- insensitive strain measurements.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.