Microcomb-enhanced BOTDR

In this work, we propose, for the first time, a novel BOTDR concept based on optical microcomb, by leveraging its outstanding advantage of frequency multiplexing. Through theoretical analysis and simulations, we found that modulation instability (MI) is the major source of crosstalk between the microcomb lines and the increase in noise during the transmission of the microcomb. Therefore, a strategy called spectral-temporal interleaving (STI) is proposed and demonstrated to solve the problem, leading to a significant improvement in the SNR of Brillouin signals and, hence the performances of the BOTDR. It is verified by experiments that such microcomb-enhanced BOTDR can achieve a temperature measurement accuracy of 0.095°C, which is more than one order of magnitude higher than that of a generally conventional BOTDR with a single-frequency laser source. This technique will benefit all the distributed optical fiber sensing technologies based on Brillouin backscattering effects, such as BOTDR, BOTDA, etc.