The effects of the intensity modulation (IM) of light source on fiber-distributed sensors based on Brillouin optical correlation domain analysis (BOCDA) are analyzed by numerical simulation, and the results are experimentally confirmed. We show that the shape of the Brillouin gain spectrum in the BOCDA system has a particular dependence on the optical spectrum of light source and that it can be controlled and tailored by proper modification of the optical spectrum using an additional IM. In the experiments, we applied several IM waveforms based on the simulation results for confirmation. Additionally, a distributed strain measurement along a 1-km optical fiber with a 30-cm spatial resolution is demonstrated by applying a proper IM scheme, which is the longest range reported using the BOCDA system.
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