Dr. Roghaieh Parvizi,
Volume 6, Issue 2 (10-2012)
Abstract
we investigate the temperature-dependences of the Brillouin frequency shift in three different kind of single-mode fibers using a heterodyne method for sensing temperature. Positive dependences coefficients of 0.77, 0.56 and 1.45MHz/0C are demonstrated for 25 km long single-mode fiber, 10 km long non-zero dispersion shifted fiber and 100 m photonic crystal fiber, respectively. The results indicate that microstructure fibers with a partially Ge-doped small core have great potential for fiber Brillouin distributed sensing.
Dr Roghaieh Parvizi,
Volume 7, Issue 1 (6-2013)
Abstract
We have investigated and developed a theoretical approach to explore stimulated Brillouin scattering (SBS) phenomena in single mode fiber. SBS happening threshold power condition has been studied in terms of fiber parameters and input pump power. To assess threshold power precisely, the pump depletion effect and fiber loss has been included by employing 1% criterion. The threshold exponential gain Gth can be anticipated by this simulation which strongly depends on the fiber length Brillouin gain content and effective area. The value of Gth is not a constant as usually assumed in the literature and its value is 4 for the longer lengths and between 10 and 18 is for relatively shorter lengths. This simulation can anticipate the optimum length of fiber against the every launched pump power to generate SBS effect.
Dr. Morteza Janfaza, Dr. Hamed Moradi, Mr. Morteza Maleki,
Volume 15, Issue 2 (7-2021)
Abstract
Graphene and molybdenum disulfide (MoS2), as two of the most attractive two-dimensional (2D) materials, are used to improve the temperature and strain sensing responses of the few-mode fibers (FMFs). The temperature and strain effects are detected based on distributed optical fiber sensors equations, where the Brillouin scattering (BS) is investigated for the FMF tapered region. For this purpose, the 2D materials were assumed as cover layers on the tapered FMF to enhance its sensitivity. Graphene and MoS2 are used as the cover layer on the FMF cladding at a distance of 10 μm from the core, and the impact of the number of material layers is investigated. By increasing the graphene layers, the temperature and strain sensitivities increase (3% and 16%, respectively) due to the rise of the inter-modal interference of the FMF. Moreover, the increasing of the MoS2 layer number improves the temperature sensitivity by 28% but shows a lower impact on strain sensitivity (about 13%). The advantage of MoS2 with respect to graphene originates from the imaginary part of the refractive index of graphene (assumed with chemical potential of 0.4 eV at the working wavelength of 1550 nm), which leads to a lower effective index of the tapered region, hence lower sensitivities. This sensitivity enhancement can improve the performance of the BS-based sensors for local detection of the parameters under-investigation in multi-parameter sensors.
