Impact of non-Lorentzian laser phase noise on Φ-OTDR performance

Abstract

We highlight the importance of the laser source phase noise in sensing applications and show that the standard Lorentzian linewidth criterion is not sufficient to characterize the performance of a sensing system. We then derive a laser linewidth related to the phase noise spectral region of interest, according to the length of the fiber to sense. This is illustrated in a setup based on coded interrogation and with two sensing dedicated laser sources.