Opt Lett. 2018 Oct 15;43(20):5078-5081. doi: 10.1364/OL.43.005078.
Direct current modulation of a semiconductor laser is a key method adopted in most optical correlation-domain distributed Brillouin sensors such as Brillouin optical correlation-domain analysis (BOCDA) and reflectometry (BOCDR) for localizing the sensing position by synthesis of an optical coherence function. We report that distributed measurement of Brillouin frequency by the BOCDA or BOCDR system can suffer significant distortion caused by phase delay between output power and frequency variations of the modulated light source. We calculate characteristics of the distortion by numerical simulations, and compare the results with experimental data obtained by a BOCDA system for confirmation. Our results show that a maximum error of more than 30 MHz can occur in Brillouin frequency measured under ordinary operating conditions with MHz-order direct current modulation.
半导体激光器的直流调制是大多数光学相关域分布式布里渊传感器（如布里渊光相关域分析（BOCDA）和反射计（BOCDR））中采用的关键方法，通过合成光学相干函数来定位传感位置。我们报告说，由 BOCDA 或 BOCDR 系统进行的布里渊频率分布式测量可能会受到调制光源的输出功率和频率变化之间的相位延迟引起的显著失真。我们通过数值模拟计算了失真的特性，并与 BOCDA 系统获得的实验数据进行了比较，以确认结果。我们的结果表明，在普通工作条件下，使用兆赫兹级直流调制时，测量的布里渊频率可能会出现超过 30 MHz 的最大误差。
