Brillouin scattering properties in partially chlorinated plastic optical fibers estimated with ultrasonic pulse-echo technique

Abstract

With their high thermal stability compared with other plastic optical fibers (POFs), partially chlorinated graded-index POFs (PCGI-POFs) are a promising candidate to develop the sensing heads of Brillouin-based distributed strain and temperature sensors. In this study, the Brillouin frequency shift (BFS) and its temperature dependence in a PCGI-POF are estimated by using ultrasonic pulse-echo technique. The estimated BFS is ~4.43 GHz with its temperature coefficient of approximately –6.9 MHz/K at 1550 nm. Its absolute value is ~5.8 times as large as that of silica single-mode fibers, and even larger than that of a perflurointated GI-POF. Its fracture strain of ~3.0% (mostly in elastic region) is small compared with other POFs, and so it appears difficult to estimate the BFS dependence on strain in a PCGI-POF with this technique. These experimental results imply that the Brillouin scattering in PCGI-POFs is potentially applicable to highprecision temperature sensing.