Numerical simulation for optimization of temporal gatings in Brillouin optical correlation domain analysis

Abstract

Brillouin sensors have the potential to measure strain or temperature distribution along the optical fiber, by determination of the Brillouin frequency shift (BFS). The Brillouin optical correlation domain analysis (BOCDA) is an important technique in Brillouin sensors, having great spatial resolution over a restricted measurement range, comparing to other systems, such as the Brillouin optical time domain analysis (BOTDA). To elongate the restricted measurement range, temporal gating techniques have been proposed and demonstrated, but the influence of these techniques on the performance of the BOCDA system or the parameter requirement for system optimization have not been investigated. In this report, we first determine a simulation method to calculate the BOCDA output with temporal gatings and find out that the phase relation between the gating pulses and the sinusoidal frequency modulation (FM) may change the system output. Although that influence can be neglected for most cases, the phase optimization can make the system output approach the ideal case that the temporal gating is not being applied. Finally, calculations of system output for different gating pulse lengths are held, showing that the pulse length does not have to strictly match one period of the sinusoidal FM of the laser source.