Open AccessTwo-wavelength phase-sensitive OTDR sensor using perfect periodic correlation codes for measurement range enhancement, noise reduction and fading compensation
Author(s) -
Mikel Sagues,
Enrique Piñeiro,
Enis Cerri,
Aldo Minardo,
Avishay Eyal,
Alayn Loayssa
Publication year - 2021
Publication title -
optics express
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.394
H-Index - 271
ISSN - 1094-4087
DOI - 10.1364/oe.413047
Subject(s) - optics , wavelength , optical time domain reflectometer , phase (matter) , phase noise , differential phase , rayleigh scattering , physics , materials science , fiber optic sensor , optical fiber , polarization maintaining optical fiber , quantum mechanics
We demonstrate a two-wavelength differential-phase-measuring OTDR sensor that uses perfect periodic correlation phase codes to enhance the measurement performance. The two-wavelength technique extends the measurement range of OTDR sensors by synthesizing a virtual longer-wavelength measurement from two simultaneous measurements of phase using different lasers. This increases the range free from phase unwrapping errors. However, we find that the application of this technique greatly increases the relative measurement noise. To compensate for this issue, we introduce the use of optical pulse compression using perfect periodic correlation phase codes to increase the measurement signal-to-noise ratio and also to facilitate the simultaneous compensation of Rayleigh and polarization fading. In addition, we apply a method to further reduce the relative noise that is added to the two-wavelength measurement by using the synthetic wavelength measurement to unwrap the differential phase measured with a single wavelength. All this is highlighted in a 1-km sensing link in which up to 20-cm spatial resolution and 12.6 p ϵ / H z strain sensitivity are demonstrated as well as a 67-fold enhancement in measurement range compared with the use of the conventional single-wavelength method.