Artur Guzik

Hybrid Brillouin-Rayleigh distributed sensing system

The paper deals with the design and principles of the hybrid Brillouin-Rayleigh sensing system. The system is capable of separating strain and temperature values in single SM fiber and offers spatial resolution as high as 2 cm. Furthermore, the paper introduces a method to determine required separation coefficients for optical fiber cables. Finally, it presents several validation examples and results of industrial applications.

Synthetic Spectrum Approach for Brillouin Optical Time-Domain Reflectometry

We propose a novel method to improve the spatial resolution of Brillouin optical time-domain reflectometry (BOTDR), referred to as synthetic BOTDR (S-BOTDR), and experimentally verify the resolution improvements. Due to the uncertainty relation between position and frequency, the spatial resolution of a conventional BOTDR system has been limited to about one meter. In S-BOTDR, a synthetic spectrum is obtained by combining four Brillouin spectrums measured with different composite pump lights and different composite low-pass filters. We mathematically show that the resolution limit, in principle, for conventional BOTDR can be surpassed by S-BOTDR and experimentally prove that S-BOTDR attained a 10-cm spatial resolution. To the best of our knowledge, this has never been achieved or reported.

Validation of TW-COTDR method for 25km distributed optical fiber sensing

The paper reports results of the long distance (25 km range) distributed optical fiber sensing by means of Tunable Wavelength Coherent Optical Time Domain Reflectometry (TW-COTDR) method. The tests were designed to verify the accuracy and repeatability of the method in long distance measurements, as well as compatibility with various optical fiber types. Results demonstrate the capability of the method to detect strain or temperature changes over long distances. This proposed method is compared to Brillouin sensing techniques, into the same fibers. Unlike the Brillouin-based methods, measurement uncertainty does not increase with increasing distance. We demonstrated 0.16°C uncertainty at 21km.

Monitoring of the ground settlement during a tunnel excavation using 4D optical fiber sensing system

In this paper we present an engineering application of optical fiber distributed sensing for monitoring of the ground settlement during a tunnel excavation. The design, installation methods, and implementation of 4D (space plus time) warning system are outlined. The ground settlement was closely monitored for entire 6 months of tunnel construction process, revealing a wide range of geomechanical phenomena. Obtained on-line vertical displacements allowed engineers to control the excavation speed and monitor ground settlement, contributing substantially to the overall reliability and safety.