SPLICED OPTICAL FIBER WITH SPLICE PROTECTION, CURRENT SENSOR WITH SUCH A SPLICED OPTICAL FIBER AND METHOD FOR PROTECTING THE SPLICED OPTICAL FIBER Russian patent published in 2021 - IPC G02B6/255 

FIELD: fiber optics.

SUBSTANCE: invention relates to a spliced optical fiber, a fiber-optic current sensor containing such a spliced optical fiber, and a method for protecting the splice of a spliced optical fiber. The claimed spliced optical fiber (2) contains the first and second polarization-stabilized optical fibers (3a; 3b), which are connected to each other by one of their ends by splicing, as a result of which a splice (3) is formed at the point of their connection, and a protective tube is placed around the spliced optical fiber (2), covering at least an uninsulated segment of the spliced optical fiber (2), which includes a splice (3). The first end and the second end of the protective tube (7) are hermetically sealed with the spliced optical fiber (2) by means of the first and second sealing nodes (9) to protect the splice (3) from the effects of mechanical stress and/or moisture. In this case, the protective tube (7) has such a length (L₀) that an uninsulated segment (8a) of the spliced optical fiber (2) containing the splice (3), and an isolated segment of the spliced optical fiber (2) at each end of the uninsulated segment (8a) are located inside the protective tube (7). The protective tube (7) is characterized by such a length (L₀) that the first distance (L₁) from the first end (11a) of the protective tube (7) and/or from the first sealing node to the location of the splice and the second distance (L₂) from the location of the splice to the second end (11b) of the protective tube (7) and/or the second sealing node exceed or are equal to the specified minimum distance L_m, and the minimum distance L_m is selected so that it satisfies the following equation:

,

where the X_o value denotes the maximum guaranteed coefficient of polarization extinction of the splice (3); the X_s value denotes the guaranteed coefficient of polarization extinction at the sealed ends (11a; 11b) of the protective tube (7); the value A(L_m) denotes the coherence function of the length of the polarization-stabilized fiber (3a; 3b) and the Fourier transformation of the optical power spectrum; and the X_m value denotes the specified maximum permissible oscillation of the polarization extinction coefficient; in this case, in particular, X_o ≤ (-25) dB, X_s ≤ (-30) dB, and X_m ≤ 0.01% to maintain fluctuations in the scale factor of the protected splice (3) at a level below ±0.03%.

EFFECT: increase in measurement accuracy by improving the protection of splices in spliced optical fibers from the effects of mechanical stress and/or moisture.

15 cl, 4 dwg