High-temperature sensitivity in stimulated brillouin scattering of 1060 nm single-mode fibers

With the rapid advancement of Yb-doped fiber lasers (YDFL) whose output wavelength is near 1060 nm, passive fibers to carry the high optical power at the spectral range are also gaining significant importance. Stimulated Brillouin scattering (SBS) in the passive fibers connecting components in the lasers, especially, can set a fundamental limit in the power handling of YDFL systems. We experimentally analyzed SBS characteristics of passive single mode fibers (SMF) at a wavelength of 1060 nm. For two types of SMFs (Corning HI1060 and HI1060Flex), the Brillouin frequency (ν_B), its linewidth (∆ν_B), and their variations with respect to the input laser power and the surrounding temperature were experimentally measured, along with the SBS threshold power (P_th). The optical heterodyne detection method was used to identify temperature-dependent SBS characteristics of fibers, and we found SMFs at λ = 1060 nm showed a temperature sensitivity in SBS frequency shift more than 40% higher than in conventional SMFs operating in C-band. Detailed procedures to measure the SBS properties are explained, and a new potential of 1060 nm SMF as a distributed temperature sensor is also discussed.