%0 Journal Article 
%A Fidalgo Martins, Hugo
%A Martín López, Sonia
%A Corredera, Pedro
%A Filograno, M. L.
%A Frazão, O.
%A González Herráez, Miguel
%T Coherent noise reduction in high visibility phase-sensitive optical time domain reflectometer for distributed sensing of ultrasonic waves
%D 2013
%@ 0733-8724
%U http://hdl.handle.net/10017/26359
%X Phase-sensitive optical time domain reflectometry (\phi \hbox{OTDR}) is a simple and effective tool allowing the distributed monitoring of vibrations along single-mode fibers. Up to now, \phi {\rm OTDRs} have been used mostly for the measurement of sub-kHz vibrations, normally in the context of intrusion sensing. In this paper, the authors present an experimental and theoretical description of a high-visibility \phi {\rm OTDR} and its performance when used for ultrasonic vibration measurements. The use of a semiconductor optical amplifier in the setup allows to suppress coherent noise and also to improve the spectral response of the pump pulses. These two advantages greatly decrease the detected intra-band noise thus allowing frequency measurements in the limits set by the time of flight of the light pulses while maintaining the simplicity of the scheme, as no post-processing, extremely high coherence lasers or coherent detection methods are required. The sensor was able to measure vibrations of up to 39.5 kHz with a resolution of 5 m over a range which could go up to 1.25 km. This is the first time to our knowledge that a fully distributed measurement of ultrasonic waves was achieved. The statistical behavior of the system was also described theoretically and characterized experimentally
%K Distributed sensor
%K Optical fiber sensors
%K Phase-sensitive OTDR
%K Vibration measurements
%K Ciencias tecnológicas
%K Electrónica
%K Technology
%K Electronics
%~ Biblioteca Universidad de Alcala