Preprint Article Version 1 This version is not peer-reviewed

Development of the Nonlinearity Correction for the Laser Tuning in OFDR System Using Zero-Crossing Sampling and Self-Reference

Version 1 : Received: 8 August 2019 / Approved: 9 August 2019 / Online: 9 August 2019 (12:50:41 CEST)

A peer-reviewed article of this Preprint also exists.

Zhao, S.; Cui, J.; Tan, J. Nonlinearity Correction in OFDR System Using a Zero-Crossing Detection-Based Clock and Self-Reference. Sensors 2019, 19, 3660. Zhao, S.; Cui, J.; Tan, J. Nonlinearity Correction in OFDR System Using a Zero-Crossing Detection-Based Clock and Self-Reference. Sensors 2019, 19, 3660.

Journal reference: Sensors 2019, 19, 3660
DOI: 10.3390/s19173660

Abstract

Tuning nonlinearity of the laser is the main source which will deteriorate the spatial resolution in optical frequency domain reflectometry system. We develop methods for tuning nonlinearity correction in the OFDR system from the aspects of data acquisition and also the posting-processing. A zero-crossing detection scheme is researched and implemented by a customized circuit. Equal-spacing frequency sampling is therefore achieved in real-time. The maximum sensing distance can reach to the same length of the auxiliary interferometer. The zero-crossing detection for the beating frequency of 20MHz is achieved. Then, a nonlinearity correction method based on the self-reference method is proposed. The auxiliary interferometer is no longer necessary in this scheme. The tuning information of the laser is extracted by a strong reflectivity point at the end of the sensing arm in the main interferometer. The tuning information can then be used to resample the raw signal and the nonlinearity correction can be achieved. The spatial resolution test and the distributed sensing experiments are both performed based on this nonlinearity correction method. The results validated the feasibility of the proposed method. The method reduces the hardware and data burden for the system and has a potential value on the system integration and miniaturization.

Subject Areas

optical fibers; Rayleigh scattering; optical frequency-domain reflectometry; strain measurement

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