Continuous chirped-wave phase-sensitive optical time domain reflectometry
Jialin Jiang, Zinan Wang, Zitan Wang, Zijie Qiu, Chunye Liu, Yunjiang Rao
Abstract
This Letter proposes a novel phase-sensitive optical time domain reflectometry ( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"> <mml:mi mathvariant="normal">Φ</mml:mi> </mml:math> -OTDR) with continuous chirped-wave (CCW), which can make full use of both time and frequency domain resources. The principle and benefits of CCW <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"> <mml:mi mathvariant="normal">Φ</mml:mi> </mml:math> -OTDR are elaborated. With the merit of CCW <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"> <mml:mi mathvariant="normal">Φ</mml:mi> </mml:math> -OTDR, 1.042 MHz sensing bandwidth and <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"> <mml:mn>5</mml:mn> <mml:mspace width="thickmathspace"/> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:mi mathvariant="normal">p</mml:mi> </mml:mrow> </mml:mrow> <mml:mtext>ε</mml:mtext> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:mo>/</mml:mo> </mml:mrow> </mml:mrow> </mml:mrow> <mml:msqrt> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:mi mathvariant="normal">H</mml:mi> <mml:mi mathvariant="normal">z</mml:mi> </mml:mrow> </mml:mrow> </mml:msqrt> </mml:math> strain sensitivity are achieved along a 1013 m fiber with 4.4 m spatial resolution. To the best of the authors’ knowledge, this is the first time that a <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"> <mml:mi mathvariant="normal">Φ</mml:mi> </mml:math> -OTDR achieves megahertz sensing bandwidth with metric spatial resolution, and without limiting the frequency feature of the disturbance. The good performance in long-range sensing is also verified over a 49.7 km fiber. More than that, the digital domain flexibility of the proposed scheme can be used to optimize the measured acoustic signal according to its feature and the practical needs.