Characterization of Nonlinear Temperature Dependence of Brillouin Dynamic Grating Spectra in Polarization-Maintaining Fibers

Temperature dependencies of the Brillouin dynamic grating (BDG) spectra in polarization-maintaining fibers (PMF's) are rigorously investigated. PANDA fiber, Bow-tie fiber, and PM photonic crystal fiber (PM-PCF) with different parameters are tested in the temperature range of -30 to +150 degrees C, where the linear and nonlinear temperature dependencies are quantified for each fiber. It is observed that bare PANDA and Bow-tie fibers show similar shape and magnitude of the nonlinear temperature dependence, while the contribution of the acrylate coating appears differently for each fiber. Suppression of the temperature dependence is observed in the PM-PCF, where notable effects of the acrylate coating on the birefringence are observed only below the room temperature. We also present the result of comparative measurement of the polarization beat length using the BDG analysis and the periodic lateral force method, which confirms the validity of the BDG-based birefringence measurement.