Two-wavelength phase-sensitive OTDR sensor using perfect periodic correlation codes for measurement range enhancement, noise reduction and fading compensation

• DOI: 10.1364/oe.413047
• Publication Date: 2020-12-20T22:30:07Z
• Authors: Mikel Sagues; Enrique Piñeiro; Enis Cerri; Aldo Minardo; Avishay Eyal; Alayn Loayssa
• Keywords: Optical time-domain reflectometer; Phase compensation

We demonstrate a two-wavelength differential-phase-measuring OTDR sensor that uses perfect periodic correlation phase codes to enhance the measurement performance. The technique extends range of sensors by synthesizing virtual longer-wavelength from two simultaneous measurements using different lasers. This increases free unwrapping errors. However, we find application this greatly relative noise. To compensate for issue, introduce use optical pulse compression increase signal-to-noise ratio and also facilitate compensation Rayleigh polarization fading. In addition, apply method further reduce noise is added synthetic wavelength unwrap differential measured with single wavelength. All highlighted in 1-km sensing link which up 20-cm spatial resolution 12.6 <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"> <mml:mi>p</mml:mi> <mml:mi>ϵ</mml:mi> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:mo>/</mml:mo> </mml:mrow> <mml:msqrt> <mml:mi>H</mml:mi> <mml:mi>z</mml:mi> </mml:msqrt> </mml:math> strain sensitivity are demonstrated as well 67-fold enhancement compared conventional single-wavelength method.