Brillouin scattering in plastic optical fibers: Fundamental properties and sensing applications

We review the fundamental properties of Brillouin scattering in a perfluorinated graded-index polymer optical fiber (PFGI-POF) at 1.55 μm, and their potential applications in strain and temperature sensing. First, the Brillouin frequency shift (BFS), Brillouin bandwidth, and Brillouin gain coefficient are clarified to be 2.83 GHz, 105 MHz, and 3.09×10^-11 m/W, respectively, which are compared with those of silica fibers. Next, we investigate the BFS dependences on strain and temperature. They show negative dependences with coefficients of -121.8 MHz/% and -4.09 MHz/K, respectively, which are -0.2 and -3.5 times as large as those in silica fibers, indicating that the Brillouin scattering in PFGI-POFs can be potentially applied to high-accuracy temperature sensing with reduced strain sensitivity. Then we summarize the recent progress on the methods for enhancing the Brillouin signals in PFGI-POFs, which is highly required for practical applications. Finally, we present our conclusions and discuss the future prospects for developing distributed strain/temperature sensing systems based on Brillouin scattering in POFs.