Differential pulse-width pair BOTDA with fast fall-time pulses

In this work we demonstrate the possibility to improve the spatial resolution in differential pulse-width pair Brillouin Optical time-domain Analysis (DPP-BOTDA) by reducing the fall time of the optical pump pulses. It is shown that while rise time has a negligible influence on spatial resolution, the fall time of the pump pulses determines the spectral purity of the acquired Brillouin gain spectra for a given perturbation width. Experimental and numerical results confirm the improvement associated to the use of optical pulses with shorter fall time.