Strength properties of femtosecond-induced defects and weak Bragg gratings for distributed optical fiber sensors

• Published in: Optics and laser technology 2023-07, Vol.162, p.109271, Article 109271
• Main Authors: Butov, Oleg V., Przhiialkovskii, Dmitrii V., Lopunov, Alexey I., Pnev, Alexey B.
• Format: Article
• Language: English
• Subjects: Distributed fiber sensors; Mechanical reliability; Mechanical strength; Weak fiber Bragg gratings; Weibull
• ISSN: 0030-3992; 1879-2545
• DOI: 10.1016/j.optlastec.2023.109271

•The mechanical strength of weak reflectors in the form of point defects or weak fiber Bragg gratings inscribed by point-by-point method using femtosecond radiation was systematically investigated for the first time. Such reflectors are widely used in perspective phase-sensitive distributed sensor system.•Weibull parameters for induced defects and fiber Bragg gratings were found.•The dependence of the Bragg gratings mechanical strength on the femtosecond pulse energy was shown and analyze. One of the possible ways to increasing the sensitivity of distributed fiber sensors is to create point defects or weak Bragg gratings in a sensitive optical fiber serving as artificial reflectors. Such reflectors can be created by means of femtosecond laser radiation. However, after the inscribing such structures, a noticeable decrease in the mechanical reliability of the sensor fiber can be observed, which can be critical for the fabrication and operation of sensor cables. The paper reports the results of a study of the point defects and weak fiber Bragg gratings strength characteristics created for distributed sensor systems, depending on the parameters of the laser radiation used to inscribe them.